Typically, “stealing” is when you have a hand that is not good enough to raise, but you still raise, considering your position, your table image, the opponents' table image, how often the players in the blinds defend them, and finally hoping that your opponents do not have a good enough hand to call your raise.
Stealing from UTG works best when other players at the table are afraid of you and/or are very conservative. They may feel that you do not have a particularly good hand, but they feel that you can outplay them after the flop. Of course, this is the advantage that poker professionals have over their opponents.
I first noticed this action in a WSOP tournament. It was the middle phase of the tournament, and poker professional Erik Seidel was in the UTG position. He had only 15 big blinds. Erik raised 3x, representing a very strong hand, and that was enough for all his opponents to fold.
In the next orbit, in the same position, he did the same action again, and again everyone folded, not wanting to tangle with him. At that time, I thought he was just getting very good hands, but later I learned that these are just actions that poker professionals take to combat the constant increase in blinds.
Erik's image is that of a smart, conservative, and tight player. His opponents at the table were also conservative and waiting for good hands. Putting all these things together, it was very easy for him to steal blinds from what seemed like a very unfavorable position.
