Files that contain the .txt file extension are files that store unformatted generic text contents. These files can be created by almost any text editing or word processing application, however, the TXT file format does not support features and functions such as tables, graphics, bolding or italics.Text files that are created in the TXT file format are structured as a series of text lines. These files are considered to be universal platform files and can be opened on almost any operating system including mobile devices.Popular applications that save unformatted text documents with the .txt extension include Notepad and TextEdit. TXT files contain very little formatting but match accepted format sets by the system terminal or simple text editor. TXT files are universal due to the ability for any text-based program to read TXT files. TXT files are capable of using Unicode to make it easier for various language users to use the files