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A client It is a PC or software that accesses a server and retrieves special services or data from it. It is the client's job to standardize the requests, transmit them to the server and process the data obtained so that they can be displayed on an output device such as a screen. A client does not run server tasks, instead it is basically an intermediate element. Typical clients are web browsers or email clients.

Development and its operation

Since the 1960s, customers serve to enable communication between hardware and servers. One of the oldest protocols is the Telnet protocol. Even today clients work in a similar way. The client sends a request to a server or to several servers and receives data that it interprets and sends in a readable way to a user. The client must use a specific protocol to communicate with the server.

To make the data available to other apps, there are two different data caching options, either on the server or client side. A widely used option to store user data on the client is cookies.


At this time the following clients are used many times:

  • Operating systems: access to the server through the command line using the Telnet protocol
  • Web navigator: Communication between the server and the browser is carried out through the HTTP protocol. Finally, the browser evaluates the received HTML documents or JavaScript apps.
  • Email clients: Even retrieval of emails from a server is done with a client function. Common protocols are POP3, SMTP, or IMAP.
  • MMPORG: In online role-playing games, the installed software acts as a client, which retrieves and provides the information necessary for the game from a server.
  • Thin Clients: Used for apps that run only on a server and require minimal hardware. Cloud solutions would be an example of this.
  • DNS clients: These clients automatically work in the background and obtain the appropriate IP address at a URL from the appropriate DNS server.
  • Apps supported on the web: as web analysis tools like Google Analytics, working with clients.
  • VPN Clients: These clients establish a secure connection between a server and a computer through a VPN (Virtual Private Network).

Rich customers vs. thin clients

Rich clients use the server as little as possible and perform most of their tasks locally. These clients are generally absolutely modular systems like development environments. On the contrary, thin clients work with the least viable hardware and they try to do all the tasks on the server side.

Relevance for SEO

When programming web pages, their presentation must be tested with different clients, that is, web browsers, because in many cases there are differences depending on the CMS that impact usability and, therefore, usually in addition to the number of conversions. The adjustment of the webs to the respective clients and the proof of the visualization of contents in different browsers belongs, therefore, within the scope of SEO.