A pin involves attacking a piece that cannot escape the attack without allowing the capture of a more important one, sheltered behind it in the same line.
Let’s look at the following diagram:
The bishop, queen, and rook can nail a piece. The example above is of a diagonal bishop dunk. The next position shows a tower pin.
Two important details should be added to define a dive. First of all, a piece can be nailed, because it covers an important square. For example:
Second, if a piece is nailed because it is in line with its king, then its paralysis is total.