How to take screenshots

A version of this was originally posted another post about capturing tweets.

How to take screenshots
On desktop computers people may want to INCLUDE the URL in the address bar but NOT INCLUDE their bookmarks. If so they can usually use the VIEW option in their browser to temporarily hide their bookmarks toolbar (and any other toolbars) to neaten the captured image. They can also resize the entire window and use the Ctrl+- (the Ctrl or Command* key plus the hyphen key) to reduce the size of the text on the screen. Ctrl++ (Ctrl / Command and the + key) to embiggen it again :)

*Command = for Mac keyboards

To take a screenshot on a Windows desktop PC or laptop
• Look for 'Print Screen' on the keyboard which is likely to be spelled Prt Scr.
• Press it to take a picture of the entire screen or press the Alt key first and then Prt Scr to take a snapshot of just the active window.
• This silently copies an image of the screen, or part of it, to the clipboard (it doesn't send it to the printer).

If you open Paint (free with Windows) or Word you can paste it in (keyboard shortcut is Ctrl+V). In Paint you can edit the image.

To take a screenshot on a Mac laptop
Note that 'Command' = the ⌘ key
Command+Shift+3     Capture the entire screen to a file
Command+Shift+Control+3     Capture the screen to the Clipboard
Command+Shift+4     Capture a selection to a file
Command+Shift+Control+4     Capture a selection to the Clipboard       
Source: http://support.apple.com/kb/ht1343

You can use the Preview tool (free with Macs) to do some basic editing of the image.

To take a screenshot on an iPhone
Press the on/off button (at the top right) and the 'home screen' button at the bottom. This will copy whatever's on your screen to your camera roll which you can then email to yourself (private) or upload to image sharing services (public).

To take a screenshot on an Android phone (v4.0 and above)
Press and hold the power and 'volume down' buttons simultaneously - h/t @ErisianLib
More at http://www.pcadvisor.co.uk/how-to/google-android/3446798/how-take-screenshot-on-android-phones-tablets/

To take a screenshot on a Samsung S3 Mini
Press and hold the 'home' and 'on/off' (power) button simultaneously - thanks to @Jackpot73 for the info. 

To take a screenshot on a Windows 8.1 phone
Press 'power button' and 'volume increase/up' at the same time - info from @Flatsquid, thank you

To take a screenshot on a Sony phone
It's power and volume down simultaneously, according to @clangyandjammy - thanks