As a Mac newbie I was shocked that I do not have to purchase an additional software to make screenshots of the desktop or windows.

The article „How to capture a screen shot with Mac OS X“ told me how it goes.

Screenshots as PNG files saved to your desktop

• Cmd + Shift + 3: Entire desktop
• Cmd + Shift + 4: Select area

Screenshots as PNG files copied to the clipboard

• Cmd + Ctrl + Shift + 3: Entire desktop
• Cmd + Ctrl + Shift + 4: Select area

Not the most intuitive way of doing, but it’s free and working and uses PNG instead of TIFF.