Before opening a computer, I often hear advice to touch something that is "grounded" - a computer case for example, or a heating element - to avoid damaging the sensitive electronic equipment through static discharge.

What exactly is true here, and what are the do's and don'ts.

• Touching what objects will actually work, and what won't? If I touch a computer case, does it matter what it stands on, and whether it is connected to an outlet? What other ways are there to protect the equipment from a static discharge than touching something grounded?

• Are there common pieces of clothing that I shouldn't be wearing when working inside a computer, for example a woollen pullover?

There is a lot on Google, but there seem to be many contradictions and misconceptions out there, so I think this is a question worth having here.