Our web hosting glossary provides clear, easy-to-understand definitions of essential hosting terms. Created for both beginners and experienced users, it covers everything from core hosting concepts to developer and CMS terminology, helping you confidently navigate the world of web hosting.
General Hosting Terms
20i
Web hosting company that offers high-performance cloud, reseller, VPS and managed hosting services for agencies, freelancers and businesses with its own control panel and 24/7 expert support. Winner of ‘Best Web Host’ in the PC Pro Awards
Bandwidth
The amount of data that can be transferred between a website and its users over a given time. Higher bandwidth supports more visitors, media, and data-heavy interactions.
Caching
The process of storing temporary copies of frequently accessed data. This reduces server workload and speeds up content delivery to returning users.
Cloud Hosting
Hosting that runs across multiple interconnected servers rather than a single machine. This distributed setup improves redundancy, flexibility, and resource availability.
Content Delivery Network (CDN)
A globally distributed network of servers that delivers website assets from locations closest to users. CDNs improve load times, performance, and resilience.
Data Centre
A secure physical facility where servers and networking equipment are housed. These sites provide power, cooling, redundancy, and security to keep infrastructure running reliably.
Dedicated Server
A full physical server allocated to a single customer or application. It provides maximum control, performance, and customisation, typically for larger or high-traffic sites.
Disk Space / Storage
The total capacity available on a server to store website files, databases, and emails. Requirements vary depending on site size, media usage, and application needs.
Downtime
Periods when a website or service is unavailable due to outages, maintenance, or technical issues. Minimising downtime is critical for user experience and business continuity.
IP Address
A unique numerical identifier assigned to devices connected to the internet. It allows browsers to locate and communicate with specific servers or hosted websites.
Latency
The delay between sending a request and receiving a response over a network. Lower latency generally results in faster website performance and better user experience.
Load Balancing
A technique that distributes incoming traffic across multiple servers. It prevents overload, improves responsiveness, and enhances availability.
Scalability
The ability to increase or decrease resources like CPU, memory, or storage as demand changes. Scalable systems maintain performance during traffic spikes or growth.
Server
A physical or virtual computer that processes requests and delivers website data to visitors’ browsers. It handles storage, processing, and network communication for hosted services.
Server Location
The physical geographic location of a hosting server or data centre. Proximity to users can influence speed, latency, and regulatory compliance.
Shared Hosting
A hosting model where multiple websites share the same server and resources. It’s cost-effective and easy to manage but offers less control and performance isolation.
Uptime
The percentage of time a server or service remains operational and accessible. Higher uptime (such as 99.9% or above) indicates greater reliability and fewer interruptions.
VPS (Virtual Private Server)
A virtualised environment that partitions a physical server into separate instances. Each VPS has dedicated resources and greater flexibility than shared hosting.
Web Hosting
A service that stores website files on internet-connected servers so they can be accessed online. Hosting providers manage infrastructure, uptime, and connectivity so users can reach a site via a domain.
Domains & DNS
A Record
A DNS record that maps a domain or subdomain directly to an IPv4 address. It’s commonly used to connect a website name to the server hosting its content.
DNS (Domain Name System)
A global system that translates domain names into IP addresses computers can understand. It acts like the internet’s directory, routing users to the correct server when they enter a URL.
Domain Name
A human-readable address used to access a website, such as example.com. It maps to a server’s IP address so users can reach sites without remembering numerical identifiers.
Nameservers
Specialised servers that store and provide DNS records for a domain. They direct DNS queries to the appropriate location so traffic reaches the correct hosting infrastructure.
Subdomain
A prefix added to a main domain to organise or separate sections of a site, like blog.example.com. It can point to different content, services, or servers while remaining part of the main domain.
TLD (Top-Level Domain)
The final segment of a domain name, such as .com, .org, or .co.uk. TLDs often indicate purpose, geography, or organisation type and are managed by domain registries.
TTL (Time to Live)
The length of time DNS information is cached before being refreshed. Lower TTL values allow faster updates, while higher values reduce lookup frequency and server load.
Control Panel
Agency Hub
20i’s all-in-one dashboard designed for agencies managing multiple clients. It centralises client management, billing oversight, and service administration in a single interface.
Client Area
A secure portal where customers manage billing, services, and account details. It typically provides access to invoices, support tickets, renewals, and product settings.
cPanel
A widely used web hosting control panel that simplifies server and website management. It offers graphical tools for managing files, databases, email accounts, and domains without needing command-line access.
Cron Jobs
Scheduled automated tasks that run at predefined intervals on a server. They are commonly used for backups, scripts, maintenance processes, or sending automated emails.
File Manager
A browser-based tool within hosting panels that allows users to upload, edit, and organise server files. It eliminates the need for external FTP software for basic file tasks.
FTP / SFTP
File transfer protocols used to upload and download website files between local devices and servers. SFTP adds encryption for improved security compared to standard FTP.
Migration Centre
20i’s free tool for quickly migrating files, databases, and emails between hosts. It simplifies transfers by automating much of the process, reducing manual configuration.
My20i
20i’s proprietary, free, and intuitive hosting control panel. It provides users with centralised management of domains, hosting services, security tools, and account features through a streamlined interface.
One-Click Installer
A tool that automatically installs applications like WordPress or Joomla. It removes manual setup steps, allowing users to deploy software quickly and easily.
StackCP
A powerful, white-label-friendly hosting control panel developed by 20i. It enables resellers and hosting providers to manage websites, databases, email, and settings under their own branding.
Twentie
20i’s one of a kind unlimited personal hosting assistant which can report on account statistics, debug code and much more.
WHM (Web Host Manager)
An administrative interface designed for resellers and server managers. It allows the creation and management of hosting accounts, resource allocation, and server configuration.
WordPress Manager
A free dashboard for updating and managing multiple WordPress websites in bulk. It streamlines tasks like plugin updates, backups, and monitoring across installations.
Reseller Hosting
Account Allocation
The process of dividing available server resources among individual client accounts. This ensures each customer receives appropriate storage, bandwidth, and performance capacity.
API Access
The ability to interact with hosting services programmatically through an application interface. It enables automation of tasks like account creation, monitoring, and integrations with external systems.
Client Billing
The process of invoicing and collecting payments from end customers for hosting services. It often includes automation for subscriptions, renewals, and usage-based charges.
Overselling
A practice where resellers allocate more total resources than physically available, assuming not all clients will use their full quota. When managed carefully, it can improve efficiency but carries performance risk.
Package Creation
Setting up predefined hosting plans with specific features and limits for resale. Packages define things like storage, email accounts, and pricing tiers offered to clients.
Private Nameservers
Custom-branded nameservers configured with a reseller’s domain (e.g. ns1.yourbrand.com). They reinforce brand identity while directing DNS queries to the hosting provider’s infrastructure.
Reseller Hosting
A hosting model that allows users to purchase server resources and resell them as their own services to clients. It enables agencies or entrepreneurs to offer hosting without managing physical infrastructure.
Resource Limits
Usage caps placed on individual accounts to control consumption of CPU, memory, storage, or bandwidth. Limits help maintain fairness, stability, and predictable performance.
White Label Hosting
Hosting where the provider’s branding is removed or hidden so services appear under the reseller’s brand. This allows businesses to present hosting as their own fully branded offering.
Performance & Resources
Autoscaling
A feature where server resources like CPU, RAM, or bandwidth automatically increase in response to traffic spikes. It ensures consistent performance during high-demand periods.
CPU Cores
The individual processing units of a server that handle computations. More cores allow a server to process multiple tasks or visitors simultaneously, improving performance.
Entry Processes
The number of concurrent requests a website can handle at one time. It directly affects the ability to manage multiple visitors without delays or errors.
High Frequency
A specialised type of web hosting optimised for speed and performance. Ideal for websites and applications that require fast loading times and high responsiveness.
I/O Limits
Restrictions on read/write operations between the server and its storage. Higher I/O limits allow faster data access, improving website speed and handling of large databases or files.
Inodes
The number of files and directories a hosting account can store. Each file or folder counts as an inode, and reaching the limit can prevent new files from being created.
PHP Workers
A process or thread that’s responsible for executing PHP code. When a request comes into a server to load a PHP page, a PHP workers will take that request and execute it. The more PHP workers you have, the more requests your website can handle without slowing down.
Process Limits
The maximum number of simultaneous tasks or scripts a hosting account can run. Limits prevent a single user from overloading the server and impacting others.
RAM
Short-term memory available to websites and applications. Sufficient RAM ensures smooth operation, faster response times, and the ability to handle more concurrent users.
Server Load
A measure of how heavily a server’s resources are being used. High server load can slow websites, while balanced load ensures optimal performance and stability.
Security
Backups
Copies of website files, databases, and settings stored for recovery purposes. Regular backups ensure data can be restored after accidental deletion, corruption, or attacks.
DDoS Protection
Measures and systems designed to prevent Distributed Denial of Service attacks. It stops malicious traffic from overwhelming servers, keeping websites online during high-volume attacks.
HTTPS
The secure version of the HTTP protocol. It encrypts data in transit, protecting sensitive information like login credentials, payments, and personal details.
Malware Scanning
The process of detecting and identifying malicious code or software on a website. Regular scanning helps prevent hacks, data theft, and site defacement.
OCSP Stapling
A performance feature that reduces SSL handshake time by appending certificate validation information to the initial connection. It speeds up HTTPS connections while maintaining security
SSL Certificate
A digital certificate that encrypts data between a website and its visitors. It ensures secure communication and enables HTTPS connections for trust and privacy.
Two-Factor Authentication (2FA)
An additional security layer requiring a second form of verification during login. It reduces the risk of account compromise even if passwords are stolen.
Web Application Firewall (WAF)
A security layer that monitors and blocks malicious traffic before it reaches your website. It protects against common attacks such as SQL injection, XSS, and other exploits.
Email Hosting
DKIM (DomainKeys Identified Mail)
An email authentication method that verifies messages are genuinely from the sender and haven’t been altered in transit. It helps prevent email spoofing and improves deliverability.
Email Forwarding
The process of automatically redirecting emails from one address to another. It’s commonly used to consolidate messages or manage multiple accounts efficiently.
Email Hosting
A service that provides servers and tools to send, receive, and store email. It allows businesses or individuals to use custom domains for professional email addresses.
Mailbox
An individual email inbox assigned to a user. It stores incoming messages, sent items, and often includes folders for organising email.
SMTP / IMAP / POP3
Standard protocols used for sending and receiving email. SMTP handles outgoing mail, while IMAP and POP3 manage incoming messages with different syncing behaviours.
Spam Filtering
Technology that identifies and blocks unwanted or malicious emails before they reach a user’s inbox. It helps reduce clutter and protects against phishing or scams.
Webmail
Browser-based email access that allows users to read, send, and manage emails without needing a desktop client. Examples include Roundcube, Gmail, or Outlook Web Access.
Developer & CMS
ElasticSearch / OpenSearch
Advanced search and indexing engines that provide fast, scalable search functionality for websites. They’re used for high-volume or complex search requirements beyond default WordPress capabilities.
Git Integration
A system for version control of code, allowing developers to track changes, collaborate, and roll back updates when needed. Many hosting platforms integrate Git for streamlined deployment.
MySQL
A widely used database system that stores website data, such as posts, user accounts, and settings. WordPress and many other CMSs rely on MySQL to manage structured data.
Object Caching
A caching method using systems like Redis or Memcached to store frequently accessed database queries in memory. It reduces database load and improves WordPress performance.
Opcache
An extension available for PHP which improves the speed and efficiency of PHP applications by caching PHP scripts.
PHP Version Control
The ability to switch between different PHP versions on a server. This ensures compatibility with themes, plugins, and newer PHP features for optimal performance.
Staging Environment
A clone of a live website used for testing changes before going live. It allows safe updates, plugin testing, or redesigns without affecting the live site.
WordPress Hosting
Hosting specifically optimised for WordPress websites. It includes features like faster caching, automatic updates, and enhanced security tailored for the CMS.
WP-CLI
A command-line tool for managing WordPress websites. It allows developers to update plugins, manage users, perform backups, and run commands quickly without using the web interface.
Billing & Plans
Acceptable Use Policy (AUP)
Rules specifying prohibited activities on a hosting service, such as spamming, illegal content, or security violations. It helps maintain a safe and reliable hosting environment.
Billing Cycle
The recurring period for which a customer is charged, such as monthly or annually. It determines how often invoices are issued and payments are collected.
Fair Usage Policy
Guidelines that set reasonable limits on resource usage for hosting accounts. It ensures no single user negatively impacts server performance for others.
Money-Back Guarantee
A period during which a customer can request a full refund after purchase. It provides reassurance and reduces risk when trying a new service.
Renewal Rate
The price a customer pays when a hosting service renews after the initial promotional term. Renewal rates may differ from the introductory cost.
SLA (Service Level Agreement)
A formal agreement outlining the provider’s uptime guarantees, support response times, and compensation for service failures.
Terms of Service (ToS)
The legal agreement that defines the rules and conditions for using a hosting service. It covers responsibilities, rights, and liabilities of both provider and customer.
Common Errors & What They Mean
301 Moved Permanently
Indicates that a page has been permanently redirected to a new URL. Browsers and search engines update their links to the new location.
302 Found
A temporary redirect to a different URL. Browsers continue to request the original URL for future visits.
400 Bad Request
The server cannot process the request due to invalid syntax or malformed data. Users may need to check the request or URL formatting.
401 Unauthorized
Access is denied because authentication is required. Users must log in or provide valid credentials to access the resource.
403 Forbidden
The server understood the request, but access is explicitly denied. The user does not have permission to view the resource.
404 Not Found
The requested page or resource does not exist on the server. Often shown when a URL is mistyped or a page has been deleted.
405 Method Not Allowed
The HTTP method used (GET, POST, etc.) is not permitted for the requested resource. The server may support other methods instead.
408 Request Timeout
The server timed out waiting for the client’s request. Slow connections or long delays can trigger this error.
409 Conflict
The request conflicts with the current state of the resource. Often occurs when editing or updating a resource concurrently.
413 Payload Too Large
The uploaded file exceeds the server’s size limits. Users may need to reduce file size or adjust server settings.
429 Too Many Requests
The client has sent too many requests in a short period. Rate limiting is applied to prevent server overload.
500 Internal Server Error
A generic server-side error indicating something went wrong. The cause may be misconfigurations, scripts, or server issues.
502 Bad Gateway
The server received an invalid response from an upstream server. Often seen with proxy or gateway setups.
503 Service Unavailable
The server is temporarily overloaded or undergoing maintenance. Users should try again later.
504 Gateway Timeout
An upstream server failed to respond in time. Often occurs when a proxy or load balancer waits too long for a backend server.