Word processing is a program that allows users to type, edit, and print documents. It has replaced typewriters and provides advantages like faster editing, formatting options, ability to print multiple copies, and email documents. The main parts of a word window include the title bar, ruler bar, tool bars, status bar, scroll bar, menu bar, and workspace. Word processing programs allow entering and editing text using keyboard, scanner, voice recognition, and include features like search/replace, spell check, grammar check, templates, and WYSIWYG display.