Greenshot - Greenshot is a free and open source screenshot tool that allows annotation and highlighting using the built-in image editor.
X Steps Recorder - A clone of Microsoft's Problem Steps Recorder, but for linux.
ShareX - ShareX is a free and open source program that lets you capture or record any area of your screen...
Folge - The fastest tool for creating step-by-step guides.
LightShot - The fastest way to take a customizable screenshot.
Dokit - The solution for disseminating know-how: work instructions, procedures, knowledge base, documentation techniques, product support, wiki enterprise.