Menchi's Connection Introduction
Why "Menchi's"? Because I wrote most of it, and I am bound to screw up, being a ~20kyu. Plus, it is too unprofessional to be part of the main site. Beginners may be interested in this, though. When it is good enough, maybe we can post it to ShapesAndConnections.
So you were just idling along, playing against another beginner, when you decide to extend your territory against Black.
Whoops! That was a bad move, I guess. Below is a simple way to extend your territory diagonally. If you haven't noticed how to do that already, make note of it now.
Check out that solid connection at the marked stones! If Black plays at a, you can play at b to connect the stones, and vice versa. This kind of connection is called a diagonal.
Here's another one that will save you some moves at low risk.
The stones form a one-point jump. Unlike the diagonal, it can be cut, but usually with useless results.
You can check out some more useful shapes and connections at the aptly named ShapesAndConnections.