Beginner's Mistakes

The black stone cannot escape.  

But see also the Two Stone Edge Squeeze for a counterexample of where this can be very useful.

Editted from a KGS game  

The three diagonal stones ( and ) are now very weak, and they are easily cut, often leading to double ataris and other nastiness.

Nastiness  

or will die.

Note however, that if it's your turn the stairs are easily and elegantly protected:

Protecting against the cuts...  

protects against the cut at both a and b!

Warp: Note however, that the double hane, resulting in something very similar to this, is not always wrong. For instance, some josekis use it (offering one stone as sacrifice in this way can have beneficial consequences in another place).

Also note that while nicely protects both cutting points, it leaves two possible peeps which, if both are answered, can make the shape quite overconcentrated.

Escape attempt  

Black's dead group in the corner desperately wants to escape and connect with the live group on the right. Black realizes that white cannot Hane to cut him off, so he plans to continue crawling on the 1st line until a connection is made. Unfortunately...

White casts a Net  

After the Net, black cannot connect.

No escape here  

The player crawling on the 1st line for escape can be given as much rope as is necessary to hang themselves with, once they finally see the Net at the end.