Ppt is a common tool for speeches and teachers. By inserting pictures, animation effects and music, what you say can be expressed more clearly.

Xls and Shanghai are commonly used office software. This is mainly a tool for making tables, which can be sorted and highlighted according to your needs. It is also a common tool for sorting out teaching results and data reports in the company.

Pdf is mainly used in compiling books, but now many such documents appear on the internet for convenience and quickness;

Txt is a text format, which can only be used to write some simple words. Because it is convenient and fast, it is often used as a notepad! !

I don't know if it is detailed enough. If you don't understand anything, you can always ask me, although you don't know much.