Explained
Timelines allow you to make animated content for your web-page. In Dreamweaver, it actually writes script called d-html or dynamic html for you.
Timelines in Dreamweaver use layers and Javascript to create animation. You can also create image swapping over time or have behaviors work after a period of time.
a. Layers only work in browser versions 4.0 and above. So keep that in mind when you do animations---some people will not be able to see them.
What kind of things can you do with your layers.
• move over time
• scale/resize over time (doesn't work in Netscape 4.0)
• hide and show over time
• change the z-index or layers stacking order over time
b. Besides layer control, in timelines, you can also have images rollover or swap out over time
c. You can also have behavior, such as going to a URL occur after a period of time in a timeline.