Glossary
Web hosting terminology, explained without marketing spin. 47 terms covering everything from bandwidth to WHOIS.
Bandwidth
The total amount of data that can be transferred between your server and users in a given period, usually measured per month. Exceeding your bandwidth limit results in overage charges or throttled connectivity.
CDN (Content Delivery Network)
A geographically distributed network of proxy servers that cache and serve static content from locations closer to end users. Reduces latency and origin server load. Examples: CloudFlare, Fastly, BunnyCDN.
CNAME Record
A DNS record that maps one domain name to another canonical name. Used to point a subdomain (e.g., www) to another domain (e.g., your main site). Essential for CDN and email service configuration.
Control Panel
A web-based interface for managing a hosting account. Common examples: cPanel (most popular), Plesk, DirectAdmin, aaPanel. Allows managing files, databases, email, domains, and server settings without command-line knowledge.
CPU (vCPU)
Central Processing Unit — the processor that executes instructions. In VPS contexts, "vCPU" refers to a virtual CPU core, which is a slice of a physical CPU rather than a full dedicated core. The number of vCPUs indicates how many tasks can be processed simultaneously.
DDoS (Distributed Denial of Service)
A malicious attack that overwhelms a server with traffic from multiple sources, making it unavailable to legitimate users. Modern CDNs and dedicated DDoS protection services can absorb and mitigate these attacks.
DNS (Domain Name System)
The system that translates human-readable domain names (yoursite.com) into IP addresses (192.0.2.1) that computers use to communicate. DNS propagation — the time for changes to spread globally — can take up to 48 hours.
Docker
A containerisation platform that packages applications and their dependencies into isolated containers. Containers are lighter than virtual machines and ensure consistent behaviour across development and production environments.
Domain
A human-readable name that identifies a website (e.g., example.com). Domains are purchased from registrars (GoDaddy, Namecheap, Gandi) and pointed to servers via DNS records. Registration is annual; letting a domain expire allows anyone else to register it.
Elasticsearch
A distributed search and analytics engine often used for log analysis, full-text search, and real-time application monitoring. Commonly deployed on VPS infrastructure for applications requiring fast data querying.
Failover
A backup operational mode where a secondary server automatically takes over when the primary server fails. Used for high-availability setups where downtime is unacceptable.
FQDN (Fully Qualified Domain Name)
A complete domain name that specifies its exact location in the DNS hierarchy. Example: mail.example.com is the FQDN for the mail server at example.com. Includes all subordinate labels.
FTP / SFTP
File Transfer Protocol (FTP) and its secure version SFTP are methods for uploading and downloading files to/from a web server. SFTP encrypts credentials and data in transit; FTP does not.
Git
A distributed version control system used for tracking changes in source code during development. Paired with platforms like GitHub or GitLab, it enables collaborative development, code reviews, and automated deployment pipelines.
Grey Listing
A spam filtering technique where the mail server temporarily rejects a message and instructs the sending server to retry. Legitimate mail servers will retry; most spam bots will not, resulting in their messages being blocked.
HTTP / HTTPS
HyperText Transfer Protocol (HTTP) is the foundation of data communication on the web. HTTPS is the secure version using TLS/SSL encryption. Modern browsers mark HTTP sites as "Not Secure"; HTTPS is required for modern web standards.
IMAP / POP3
Internet Message Access Protocol (IMAP) and Post Office Protocol (POP3) are methods for retrieving email from a mail server. IMAP syncs emails across devices; POP3 downloads and typically deletes them from the server. IMAP is the standard for most use cases.
Kernel
The core of an operating system that manages system resources, hardware communication, and low-level operations. On VPS hosting, some providers allow custom kernel installation (KVM virtualisation) while others use a shared kernel (OpenVZ).
KVM (Kernel-based Virtual Machine)
A virtualisation technology that provides full hardware virtualisation, allowing each VPS to run its own kernel and have near-bare-metal performance. Preferred over OpenVZ for workloads requiring kernel-level access or custom kernel compilation.
Load Balancer
A device or software that distributes incoming network traffic across multiple servers to ensure no single server is overwhelmed. Essential for high-availability configurations and applications with variable traffic patterns.
Managed Hosting
Hosting where the provider handles server maintenance, security updates, backups, and technical support. More expensive than unmanaged hosting but reduces operational overhead. Contrast with unmanaged hosting where you handle everything.
MariaDB
An open-source relational database management system, designed as a drop-in replacement for MySQL. Faster than MySQL in many benchmarks and free from Oracle's licensing. Standard LEMP stack component.
MySQL
An open-source relational database management system (RDBMS) widely used for web applications. WordPress, Drupal, and most PHP applications use MySQL by default. Alternatives include PostgreSQL (more feature-rich) and MariaDB (MySQL-compatible, open-source).
Nameserver
Servers that translate domain names into IP addresses. Your domain registrar points your domain to your hosting provider's nameservers, which then serve DNS records directing traffic to your server IP.
Nginx
A high-performance web server and reverse proxy. Can serve static content directly, load balance across application servers, and cache content. Typically faster than Apache for static content and handles concurrent connections better.
Node.js
A JavaScript runtime built on Chrome's V8 engine that executes JavaScript server-side. Enables building fast, scalable network applications. Popular for APIs, real-time applications (chat, live updates), and streaming services.
NVMe (Non-Volatile Memory Express)
A storage protocol designed for flash storage that minimises latency and maximises throughput. NVMe SSDs are significantly faster than SATA SSDs (1,000-7,000 MB/s vs ~500 MB/s) and are now standard in quality VPS hosting.
OpenVZ
A container-based virtualisation technology (vs KVM's full virtualisation). Lightweight and efficient but shares the host kernel, limiting custom kernel installation and some system-level operations.
PHP
A server-side scripting language used for web development. WordPress, Drupal, Magento, and many other CMS platforms are built in PHP. Currently at version 8.x, with significant performance improvements over 7.x.
PHP-FPM
PHP FastCGI Process Manager — a alternative to standard PHP-CGI with process management, adaptive spawning, and status reporting. Significantly better performance for high-traffic PHP sites than traditional CGI.
Port
A communication endpoint for data transfer. Common ports: 22 (SSH), 80 (HTTP), 443 (HTTPS), 3306 (MySQL), 25 (SMTP). Firewall rules control which ports are accessible from the network.
Private Network
A network segment isolated from the public internet, used for internal communication between servers (e.g., database server to application server). Prevents sensitive traffic from traversing the public internet and reduces attack surface.
Propagation
The time required for DNS changes to spread across the global DNS system. DNS records are cached by resolvers worldwide, and each has its own TTL. Changes can take from 15 minutes to 48 hours to fully propagate.
Redis
An in-memory data structure store used as a database, cache, and message broker. Essential for scaling PHP applications (session storage), WordPress (object cache), and any application requiring fast data access.
Root
The superuser account on Linux systems with unrestricted access to all files and commands. "Root access" means you can modify anything on the server. Should be protected carefully and used sparingly for daily tasks.
Scalability
The ability of a system to handle increasing load by adding resources (vertical scaling — more CPU/RAM) or more servers (horizontal scaling — more instances). Cloud hosting makes horizontal scaling easier than traditional infrastructure.
SLA (Service Level Agreement)
A contract between you and your hosting provider specifying guaranteed uptime (e.g., 99.9%), response times, and compensation for violations. Read the SLA carefully — "99.9% uptime" equals ~8.7 hours of downtime per year.
SMTP (Simple Mail Transfer Protocol)
The standard protocol for sending email between servers. Your web application uses SMTP to send transactional emails (password resets, order confirmations). Poorly configured SMTP is a major cause of emails landing in spam.
SSD (Solid State Drive)
Storage that uses flash memory instead of spinning platters, resulting in dramatically faster read/write speeds than traditional hard disk drives (HDD). NVMe SSDs are the fastest variant; SATA SSDs are slower but still significantly faster than HDD.
SSH (Secure Shell)
An encrypted protocol for secure remote access to servers. Replaced older, insecure protocols like Telnet. Essential for server administration. SSH keys provide password-less, more secure authentication.
SSL / TLS
Secure Sockets Layer (SSL) and its successor Transport Layer Security (TLS) are cryptographic protocols that encrypt data in transit between a user's browser and your server. Required for HTTPS. Let's Encrypt provides free certificates.
Swap
Disk space used as virtual RAM when physical RAM is exhausted. Accessing swap is orders of magnitude slower than RAM — a server that starts swapping will become extremely slow. Monitor RAM usage and upgrade before swap is used.
TTL (Time to Live)
In DNS, the number of seconds a record should be cached before being refreshed. Lower TTLs (300 seconds = 5 minutes) allow faster changes but increase DNS query load. TTLs should be lowered 24 hours before major DNS changes.
Uptime
The percentage of time a server is operational and accessible. "99.9% uptime" means the server is expected to be available 99.9% of the time — roughly 8.7 hours of allowed downtime per year. Higher percentages (99.95%, 99.99%) allow proportionally less downtime.
VPS (Virtual Private Server)
A virtual machine that provides dedicated resources (CPU, RAM, storage) within a shared physical server. More control and consistent performance than shared hosting, less expensive than dedicated servers. The standard choice for production web applications.
Webmail
Email access through a web browser rather than a dedicated email client. Popular webmail interfaces include Roundcube, Horde, and RainLoop. Most hosting providers include webmail with their email hosting packages.
WHOIS
A protocol and database for querying registered domain name owners. Domain registrars are required to collect and display WHOIS information (name, address, email) unless you use privacy/proxy registration services.
Hosting providers mentioned in this glossary
These providers are referenced throughout our glossary definitions. See our full reviews for detailed assessments.