What is an operating system and what does it do?
The job of an operating system is to provide a computing environment that is safe, secure and stable. Therefore, the OS acts as a mediator between the application software and the physical resources of a computer. This is done in order to make sure that the hardware is effectively used and the user’s work will be protected.
When booting, a computer loads its operating system into memory and runs the software. It then uses the services provided by the operating system to load and execute other programs. Programs can accomplish a wide range of tasks, such as word processing, database management, web surfing, multimedia operations or games. When finished using these programs, they could mask what has been done even if someone else tries to access them.
How do you switch between different applications on your computer or phone?
There are many ways to achieve this. For example, some operating systems offer a simple way to switch between different applications called “switching tabs” (e.g., Internet Explorer’s “tabbed browsing” feature). Other operating systems offer a more sophisticated way, such as “multiple desktops”. In Windows, these have been renamed the “Taskbar” and the “Start Menu”, respectively. Users can also switch applications by selecting them from a list (such as the “Applications” list that appears when you right-click on your computer’s desktop). You may also find that certain applications have their own unique method of switching between them, for example, many email applications and other productivity applications have a “Window List” or “Window Menu” feature which allows you to switch between specific windows of the application that is open on your computer.
Why would you want to use more than one application at a time on your device?
There are a number of reasons why you might want to do this. For example, some applications are started by default in multiple copies (sometimes called “spinning discs”); if you want to use the same application in multiple copies at the same time, this can lead to the application slowing down other applications. Similarly, it is possible that your user account requires access to more than one application at a time; for example, if you have an active chat session on IRC while using a web browser and surfing websites simultaneously. Some applications might provide different functions for different users. For example, if you can use your web browser to read email, but you need another program to send your own email, then you might want to use both applications simultaneously.
If this is what you want, there are several ways to accomplish this on different operating systems. GNU/Linux and BSD distributions commonly include tmux or GNU Screen; both provide similar functionality, allowing a server running in a terminal window to be reattached to in new terminal windows. Mac OS X includes tmux and LaunchBar; it also has SüperTerm, an enhanced version of GNU Screen.
