Open may refer to any of the following:
1. In general, open refers to something that can be accessed or viewed.
2. When referring to computer software, open commonly refers to the process of executing or running a program or accessing or reading a file. For example, if you wanted to read a word processor file you could "open" Microsoft Word a commonly used word processor program and once open select the word processor file to open. In this example, if your computer did not have a word processor installed or didn't support the file it would be unable to open the file or you would get an error.
Tip: The keyboard shortcut Ctrl+O shows the open window in most programs and allow you to choose a file to open.
3. When referring to computer hardware or other hardware devices, open refers to physically removing a compartment, such as removing the computer case cover.
5. When using FTP, open is a command used to establish a connection with a remote computer.