Question: This term seems to be quite in use in English-speaking communities. I'm curious what it is? Is it like two students code together on a single PC or what? Is this organization (whatever it is) is only used in US?

Answer: 
When in doubt, ask Wikipedia: [Pair Programming](http://en.wikipedia.org/wiki/Pair_programming). The general idea is to have one person writing code while the other scans for mistakes and cohesiveness.
Paired programming is when two developer work on the same story card sharing a single computer and keyboard. It is considered an extreme programming practice. Extreme programming takes something positive, in this case a code review, and takes it to the extreme. The benefits beyond the continuous code review are as follows:

* **Improved quality**: A pair of active programmers working on the same story card will complete the card with less defects
* **Improved productivity**: a pair is less likely to be slowed down if not outright blocked when solving a problem. Furthermore, it is harder to take an email or web vacation when you are working with a partner ... you don't want to let the partner down. You will solve the problem with a cleaner design and less lines of code when working as a pair
* **Eliminate silos of knowledge**: With rotating pairs, you will learn application and domain business knowledge across the team. The team is less likely to be blocked because Sue when on vacation and no one else knows her code.
* **Knowledge Transfer:** Rotating pairs teach new skills (engineering and domain) to each other as they work together. The level of the team will rise for everyone and the knowledge propagates through the team.
* **Team self selects:** The team learns one anther's skills and will quickly weed out someone that is not performing.