I am currently using Ubuntu 15.10. I need to highlight some sentences and/or paragraphs for easy searching but I can't find any option for this in the "Document Viewer" which is the default application for pdf files.
Try Mendeley (https://www.mendeley.com/)! It does the work like a charm!
In fact, Mendeley is more than a PDF-reader. You can use it to organize your docs and references.
Document Viewer doesn't support highlighting install another application such as FoxIt Reader. I prefer foxit because it's simple to use and if you install on Windows, Mac or mobile keep the highlighting and attachments.
To install foxit reader :
- Open Foxit website.
- Click "Free download" and it will detect operating system then click "Download".
- Extract the file you downloaded.
- Double click the .run file and install.