The basic program allows you to annotate an image with little hot spots that pop up either a link to a website of your choosing or just some descriptive text. You can also search for a previously created ThinkLInk images and remix them. This means you can edit the image to add or remove hotspots to fir your need. Thinglink is multiplatform and can be used on the computer or with the Android or iOS app.
Below is an example of a ThingLink on the human body (I can't take credit for this, it was created by a student ThingLink user). As I've done here you can embed ThingLinks into any place that allows HTML code. She decided to make the hot spots letters and numbers so that you can hover over them for more information. You can also use small target like circles as the hot spots. (If the image below isn't working, click here to see it)