One nifty feature I’ve found with my new Apple Mac Mini is that taking screenshots is real easy. If you want to capture an image of a portion of the desktop, simply type the key sequence:
cmd-shift-4
i.e. press down both the cmd key and the shift key then press the 4 key at the same time.
The Mac then displays cursors that you can drag with the mouse to grab any portion of the screen you like – press the left mouse button to begin capture then move the mouse to encompass the desired are before releasing the left mouse button to complete the capture. The image is then automatically saved as a PNG file on the desktop.
After the image is saved onto the desktop, double-clicking the image with the mouse displays the image in the Preview tool. The Preview tool contains a number of handy features, e.g. the Tools menu lets you resize the image and the File menu contains options to export the image in different formats, e.g. as a .JPG file.