Simplify the following text for a Grade 10 native English-speaking person.
Original: Adobe soon started distributing its Acrobat Reader ( now Adobe Reader ) program at no cost , and continued supporting the original PDF , which eventually became the de facto standard for printable documents on the web ( a standard web document ) .
Simplified: PDF reader software is required to read PDF documents . Examples are Adobe Acrobat , Adobe Reader and Foxit Reader .