Lexicon

Server and software terms

The short version

• A web server is the program, or the computer, that sends out web pages. Apache and nginx are two common ones.
• Browsers and servers talk using HTTP. Every reply carries a status code, such as 404.
• Many hosts run the LAMP set of software: Linux, Apache, MySQL and PHP.
• You manage a hosting account through a control panel, and move files with SFTP or log in with SSH.

Web server

A web server is the software, or the computer running it, that stores a site's files and sends them to browsers.^[1]

The software part understands web addresses and HTTP.^[1] When a request comes in, it finds the right file and sends it back.^[1]

Think of a librarian. You hand over a slip with a book's code. The librarian fetches the book and passes it across the desk.

See also: HTTP · Apache HTTP Server · nginx · Web host.

HTTP

HTTP is the set of rules browsers and web servers use to ask for and send web pages.^[1]

Each request stands alone. Neither side remembers earlier messages.^[1] So a site that keeps you logged in needs extra software on top.

Origin: the current core standard for HTTP is RFC 9110, published in June 2022.^[2]

See also: HTTP status code · HTTPS.

HTTP status code

A status code is a three-digit number a server sends back to say how a request went.^[2]

The first digit gives the kind of answer. There are five kinds.^[2] A few common ones:

• 200 OK: the request worked.^[3]
• 404 Not Found: the server cannot find what was asked for.^[3]
• 500 Internal Server Error: something went wrong on the server.^[3]
• 503 Service Unavailable: the server can't cope right now. It may be down for maintenance or overloaded.^[3]

See also: HTTP · Uptime.

Apache HTTP Server

Apache is a free, open-source web server program.^[4]

It grew out of fixes that webmasters shared for an older server. See the history page for that story. It was the most used web server from 1996 until about 2016.^[5]

Origin: Apache 1.0 was released on 1 December 1995.^[4]

See also: Web server · nginx · LAMP stack.

nginx

The program nginx, said "engine x", is a web server. It can also cache content, share out traffic and pass requests to other servers.^[6]

That makes it useful in front of other software. For example, nginx can send out a site's plain files itself.^[6] It can pass other requests on to a separate program as a reverse proxy.^[6]

Origin: nginx was first written by Igor Sysoev.^[6] It was released to the public in 2004.^[7]

See also: Apache HTTP Server · Load balancing · Cache.

Virtual host

A virtual host is one of several websites run by the same server.^[8]

Visitors can't tell that the sites share a machine.^[8] Each browser request names the site it wants. The server reads that name and picks the right site.^[2]

This is how shared hosting fits hundreds of sites on one server. For example, example.com and example.net could both live on one machine.

See also: Web server · Shared hosting.

Control panel

A control panel is a website a host gives you for managing your hosting account.^[9]

From it, you can usually manage files, databases, email and file transfer.^[9] You click buttons instead of typing commands on the server.

Origin: cPanel, one of the best-known panels, was first released in March 1996.^[10]

See also: Shared hosting · Reseller hosting.

LAMP stack

LAMP is a common set of free software for running websites: Linux, Apache, MySQL and PHP.^[11]

Each letter is one layer. Linux is the operating system. Apache is the web server. MySQL holds the data. PHP runs the code that builds pages.^[11] The P can also stand for Perl or Python.^[11]

A stack is just a set of programs that work together, one on top of another.

Origin: the name LAMP was coined in December 1998.^[11]

See also: PHP · Database · Dynamic site.

PHP

PHP is a programming language made for building websites.^[12]

PHP code usually runs on the web server.^[12] It might fetch the latest posts from a database and slot them into a page. The browser only ever sees the finished page.

Origin: PHP was created in 1994 by Rasmus Lerdorf.^[13] It first stood for "Personal Home Page Tools".^[13]

See also: LAMP stack · Dynamic site.

Database

A database is an organised store of data that software can search and update. MySQL is a common one on web hosts.^[14]

MySQL keeps data in tables, a little like a spreadsheet.^[14] A blog keeps its posts and settings in its database.^[15]

Origin: MySQL was first released on 23 May 1995.^[14]

See also: LAMP stack · Backup.

FTP

FTP, short for File Transfer Protocol, is an old set of rules for moving files between computers.^[16]

FTP does not encrypt anything. Passwords and files travel as plain text that anyone snooping on the network can read.^[17] Today SFTP is seen as its replacement, because SFTP is more secure.^[18]

Origin: the FTP standard, RFC 959, dates from October 1985.^[16]

See also: SFTP · SSH.

SSH

SSH, short for Secure Shell, lets you log in to a server over the internet and type commands safely.^[19]

It replaced older tools that sent passwords as plain, readable text.^[20] For example, the owner of a VPS might use SSH to install updates.

Origin: Tatu Ylönen designed SSH in 1995.^[20]

See also: SFTP · Unmanaged hosting.

SFTP

SFTP is a way to move files to and from a server over a secure SSH link.^[18]

It does the same job as FTP, but everything is encrypted.^[18] For example, a developer can upload a new page to a server without the password being exposed.

See also: FTP · SSH.