iPhone reboot FAQ: How do I restart (reboot) an iPhone, iPod, or iPad?
As a new iPhone user, after hearing that the iPhone may suffer from a memory leak which causes applications to become slower over time, I looked at my phone and wondered "How do I turn off my iPhone?", quickly followed by "How do I restart my iPhone?"
In my case I don't know if there really is a memory leak, but this morning -- immediately following the 2.0.1 system upgrade -- I had problems placing a call with my iPhone 3G, and I found that restarting the iPhone fixed this problem.
Several months later now, and I have not had any more problems placing phone calls, especially not like I had on the day I wrote this blog entry. I have had some iPhone slowness problems, and whenever that happens I usually reboot my iPhone, and it behaves better.
On one other note related to the iPhone power button (on/off switch), if you want to create a iPhone screenshot, you'll be using that power button again. Here's a link to my How to create an iPhone screenshot (screen capture) tutorial.