Synfig Studio creates 2D animation.
It uses new techniques to allow you to create animations quickly, with a limited budget. It can be compared to the Flash animation application. It is a very stable tool with a lot of professional features. Photographs and other backgrounds can be integrated with icons and cartoon figures to create scenarios which can communicate a particular message.
The use of animation allows you to use the power of moving images cheaply to communicate your message.
Synfig can output to animated gifs for use on the internet but it is now probably more useful to output to a video file so that it can be uploaded to video sharing sites and embedded in internet pages.
Creating a cartoon-style animation for a campaign
A solid animation solution for all major operating systems
There are good tutorials available
Animation involves a fair amount of time to learn