A file with an .ai extension is an Adobe Illustrator Artwork file that contains vector graphics on a single page. It uses points to create paths for displaying the image data, thus making it safe from losing image quality if it is enlarged. AI format finds its major usage for logos and print media. AI files can be opened with Adobe Illustrator, Adobe Acrobat DC, PaintShop Pro, and CorelDraw Graphics tools.
A file with .TXT extension represents a text document that contains plain text in the form of lines. Paragraphs in a text document are recognized by carriage returns and are used for better arrangement of file contents. A standard text document can be opened in any text editor or word processing application on different operating systems. All the text contained in such a file is in human-readable format and represented by sequence of characters.
You can also convert AI into many other file formats. Please see the complete list below.