Depending upon the rules we have found, we can classify the locks into two types.

Shared Lock: A transaction might be acquiring shared lock on a data item in order to read its content. The lock is shared in the sense that any other transaction can obtain the shared lock on that similar data item for reading purpose.

Exclusive Lock: A transaction might be acquiring exclusive lock on a data item in order to both read/write into it. The lock is excusive in the sense that no other transaction can acquire any type of lock (either shared or exclusive) on that similar data item.