Have you ever asked strangers for a ride in their vehicle, aka hitchhiking?
No I have not. Wouldn't that be dangerous?
It's probably dangerous sometimes. But it's a historically common practice worldwide.
What is it commonly practiced? Usually in rural areas?
I'm not sure exactly. Interesting thing is that the hitchhiker's method of signaling to drivers varies around the world.
What is the most common way to signal hitchhiking? 
Extending an arm out and sticking up the thumb is common in North America, United Kingdom, and most of Europe.
What about in Asia and Middle East? 
I'm not sure about those areas, but in Africa they hold their palm up
That is interesting. I do know that in some cultures, the thumb up gesture is offensive