Since the commands available in command line interfaces can be many, complex operations can be performed using a short sequence of words and symbols. This allows greater efficiency and productivity once many commands are learned, but reaching this level takes some time because the command words may not be easily discoverable or mnemonic. Also, using the command line can become slow and error-prone when users must enter long commands comprising many parameters or several different filenames at once. However, "windows, icons, menus, pointer" (WIMP) interfaces present users with many widgets that represent and can trigger some of the system's available commands.