In a nutshell, it is the world's first browser-based macro recorder. It allows you to easily record web surfing and replay it.
The web browser is probably the most frequently used software today, but many tasks are repetitious: checking on the same sites everyday, remembering passwords, submitting to search engines or testing web sites over and over again. With iMacros, you record these tasks once and then let iMacros execute them whenever you need them.
Any combination of browsing, form filling, clicking and information gathering can be recorded into a macro and iMacros even assists you during the recording with visual feedback.