PDF files can contain lengthy documents. Using the highlight feature in Adobe Reader 9 helps organize notes and makes it easier to find important information. Adobe Reader 9 is a free PDF viewing program. Users can highlight, cross out or underline sections of any PDF document that allows comments. According to Adobe, Adobe Reader 9 is cross-platform with downloads available for Windows, Mac, Linux, Solaris and mobile devices. Adobe first released Reader 9 in 2008.
Adobe Acrobat 9.0 was released. Support for version 9 ended June 26, 2013, with the last available update being 9.5.5.
Adobe Reader 9 ends compatibility with Adobe Reader Extensions 5 and 6 which permit Adobe Reader client software to save changes to filled-in forms in PDFs. Adobe Reader Extensions 6.1 and newer are still usable. Legacy PDFs will still be viewable, however they will open with the warning “This document enables Reader capabilities that are no longer enabled in this Reader version.”
The Adobe Acrobat 9 set also omitted the multiple document interface. Previous versions of Adobe Acrobat activated multiple PDF files in the same window (except for version 8 where MDI was only an alternative option and the default mode SDI). Acrobat 9 however, only uses the single document interface scheme, wherein each PDF file is activated in an instance of Adobe Acrobat. Adobe Acrobat 9 is the last version to support Windows 2000 and PowerPC-based Macintosh PCs.