What does SM mean in online novels?

In other words, while making love, I will abuse' little sufferings' again and again.

If there is wax dripping, you light a candle, and then drop it on the nipple and navel of the small receiver with wax that melts into liquid.

There are handcuffs, which are handcuffs. Cuff the limbs of the little victim separately. In the shape of' big', let the attacker do whatever he wants.

There is also a metal ring, which is widely used in BL, that is, the' little guy' is circled with a metal ring, and this desire cannot be vented.

However, SM is still used for BL, while BG is rarely used.