Terminal Services is one of the components of Microsoft Windows (both server and client versions) that allows a user to access applications and data on a remote computer over a network. 

Terminal Services is Microsoft's implementation of thin-client terminal server computing, where Windows applications, or even the entire desktop of the computer running terminal services, are made accessible to a remote client machine. Users can run programs, save files, and use network resources as if they were sitting at that computer.

With a Terminal Server, all program execution, data processing, and data storage occur on the server, centralising the deployment of programs. Terminal Server ensures that all clients can access the same version of a program. Software is installed only once on the server, rather than on every desktop throughout the organisation, reducing the costs associated with updating individual computers.