How does Olympic swimming time keeping work?

That's the question I asked. I thought the folks who stand at the end of the pool had a little button in their hands like the Jeopardy buzzer and they looked for the swimmer to touch the edge of the pool and clicked and that stopped the time for that swimmer. Well, I was wrong. My brother insisted that there was some kind of touch pad in the pool and the swimmers triggered it themselves. He was right - and forwarded me this About.com article called "Olympic Swimming Rules - Equipment, Officials, and Awarding Medals" to prove it. I am now assuming this is accurate. What the article talks about certainly has the potential to be more accurate than my idea. The touch pad timing thing is on page 3. But the article is interesting overall if you are newly interested in swimming perhaps because of all the attention Michael Phelps is bringing to the sport.