The term server has a double meaning in IT. It is used to describe a computer that makes resources available over a network, as well as the program that runs on this computer. Therefore, it is necessary to have two different server definitions:
A hardware-based server is a physical device connected to a computer network on which one or more software-based servers run alongside the operating system. An alternative term for a hardware-based server is host. In principle, any computer can be used as a host with server software.
A software-based server is a program that offers a specialized service to be used by other programs (known as clients) locally or via a network. The service offered depends on the type of server software. The client-server model is the basis of communication. When it comes to exchanging data, service-specific communication protocols are used.
Server services operating via computer networks are realized thanks to the help of client server-models. This concept makes it possible to divide tasks among different computers and allow users access to them simultaneously. Every service provided via a network requires a server (software), which is permanently on standby. This is the only way to ensure that clients, like web browsers or e-mail programs, always have the opportunity to access the server and utilize its service when needed.
The way that client and server communicate depends on the particular service and is determined by a specific transfer protocol. This can be best explained using examples of the main server types:
The primary task of a web server is to store, process, and deliver websites to clients, like web browsers and search engine crawlers. Communication between server (software) and clients is carried out via the Hypertext Transfer Protocol (HTTP) or its encrypted version, HTTPS. HTML documents and the elements incorporated in them like, images, style sheets, or scripts, are transferred this way. Major web servers include the Apache HTTP server, Microsoft Internet Information Services (IIS), and Nginx.
File servers care for the central storage of data accessible for a number of different clients via a network. Companies rely on this file management to provide multiple workgroups access to the same file. File servers protect against problems arising from various local file versions by enabling automatic versioning of files and a centralized backup of all corporate data. If access to the file server comes via the internet, then transmission protocols like FTP (File Transfer Protocol), SFTP (Secure File Transfer Protocol), FTPS (FTP over SSL), or SCP (Secure Copy) are used. In local computer networks (LAN), the protocols SMB (Server Message Block) and NFS (Network File System) are utilized.
A mail server consists of several software modules that work together to enable e-mails to be sent, received, forwarded, and retrieved. The Simple Mail Transfer Protocol (SMTP) usually handles this. Users who wish to access a mail server need an e-mail client to collect messages from the server and deliver them to the e-mail inbox. This is carried out by IMAP (Internet Message Access Protocol) or POP (Post Office Protocol).
A database server is a computer program that gives other programs access to one or several database systems via a network. Software solutions like this include Oracle, MySQL, Microsoft SQL Server, PostgreSQL, and DB2. Database servers support web servers by storing and delivering data.
Game servers (software) are specialized for online-based multiplayer gaming. They manage data from the online game and enable a synchronized interaction with the virtual world. The hardware for a game server can come from the data center of a specialized provider or locally via the home network.
A proxy server serves as a communication interface in computer networks. Acting as an intermediary, the proxy server accepts requests from the network and forwards them on via its own IP address. Proxies are used to filter communication, control bandwidths, increase availability by load balancing, or to cache data. A proxy server also offers increased anonymity because the client’s IP address is hidden behind the proxy.
DNS, or name servers, are responsible for name resolution on a network. This is central to the World Wide Web, because a DNS server will translate the human-friendly host name (like www.ionos.com) into the corresponding IP address. For further information on DNS servers and the domain name system, please refer to our article on DNS servers.
Server. (n.d.). Retrieved December 14, 2020, from https://www.paessler.com/it-explained/server
What is a Server? - Definition from Techopedia. (n.d.). Retrieved December 14, 2020, from https://www.techopedia.com/definition/2282/server