Greenshot provides a really convenient and effective way to capture screenshots in addition to editing them.
No install required just download, unzip, and execute greenshot.exe. It supports three types of screen captures; region, window, and full screen. Images can be saved as JPEG, GIF, PNG, and BMP. The screen shot can automatically save as a file, sent to a printer, clipboard, or image editor. The image editor supports drawing rectangle, ellipse, line, arrow, and add text. This screen capture tool is easy to use and can allows you to quickly add ellipses, rectangles, lines, and arrows to the image. Be warn this tool on its first execution sets itself up to be automatically when windows is started. This is easy turned off through changing its preferences. It also replaces the windows print screen key for capturing. If you are looking for a screen capture with more capabilities than the windows print key this might be it.
Greenshot is Open Source and runs on all varieties of Windows. There’s also a portable version (which weighs in at only 160k) available for on-the-go screenshots from your USB flash drive.
Please visit the Official web site for more information
Activate region mode by hitting the Print key on your keyboard or by choosing Capture region from the context menu.
Left-click and drag to define a rectangular area you want to be shot.
After releasing the mouse button, the image editor window will open for further editing of your screenshot.
For shooting the region again later, choose Capture last region from the context menu.
Activate window mode by hitting Alt + Print on your keyboard or by choosing Capture window from the context menu.
Click the window you want to be shot.
After clicking, the image editor window will open for further editing of your screenshot.
If you want to shoot the complete screen, just press Ctrl + Print on your keyboard or choose Capture full screen from the context menu.
The complete screen will be shot instantly, the image editor window will open for further editing of your screenshot.
More features on the official Greenshot site