You can add interactivity to your PDF documents by adding hyperlinks. This is a straight-forward process in Indesign, which we explore when creating interactive documents in Day 2 of our Adobe Indesign course. 
An interactive document is created in the same fashion as a regular print document or PDF. You may wish to add your hyperlink as part of a header or footer. For example, to create a link to the Sydney Uni website first create a text box with the text The University of Sydney, or sydney.edu.au.
Then highlight the text and go to Window > Interactive > Hyperlinks. Click on the panel options fly-out button (top right) > New Hyperlink from URL (if you’ve copied the whole URL including the www), or New Hyperlink, in which case you have to type in the URL. This will create a new hyperlink in the panel. Double-click on it to check the URL is correct (eg.http://sydney.edu.au/).
In CS3 and CS4 go to Appearance: Type > change to Invisible Rectangle – otherwise the link will have an ugly black rectangle around it. This step is not necessary in CS5 and later.
Various types of hyperlinks are possible – to websites, to other pages in the document, chapter headings in a long document, even email addresses. You can also add a hyperlink to an image instead of to text.
Then create the PDF as normal: File > Export > Type: Adobe PDF (Interactive). In the Buttons & Media section tick Include all > OK > OK. The hyperlinks will be active when the document opens in Adobe Acrobat or Adobe Reader.
Whether you’re a complete beginner or self-taught, our custom courses will help you gain self-confidence in your Indesign workflow, as well as adding to your professional skill-set. See many examples of our clients’ work on our Facebook site.
The Sydney Indesign User Group in Sydney meets bi-monthly, and is a free forum for designers to discuss topics and the latest Indesign features.
Other related Indesign Blog Posts:

• Indesign images and text
  
• Indesign workflow
• Indesign templates
• Indesign page numbers
• Indesign for fashion