You can use a keyboard shortcut or click on the program icon on the system tray to take the screenshots. Once you capture what you want, you can upload it directly or edit it first.
The editing mode is pretty simple, but it still lets you add geometric shapes, paint the captured image, add text, and change the format. Nothing too complicated, but still useful.
JShot is a good alternative to a huge number of other similar programs that you can find out there. It's fast, efficient, and easy to use.