PDF is a file format for electronic documents. You can view PDF files on a computer, but you will need a program to read them. There are several different programs, and you will need to find one that you like. PDF is a good option for your smartphone or tablet, because you can view PDF files on your mobile device. You can do things like write a note, draw a diagram, or add an image to the document. If you are using a tablet, you can also make a presentation. You can also add music and video to your presentation. This is all very easy to do, and it is a very good option for your smartphone or tablet. You can add text to the document as well. You can also use your smartphone or tablet to make a copy of the document for yourself. This is very useful, especially for people who do not have access to a computer.