As a DBA, I am always interested to find whether blocking is going on, in my environment or not? How long blocking exists? Which are the queries/SPs creating blocking etc.
Blocking generally occurs when one SQL Server connection (user process or application process) places a lock on a table or a number of rows and a second connection attempts to read or modify the data under the lock by first connection. Depending on the type of the lock, this can cause the second connection to wait until the first connection releases its lock. A blocked connection waits indefinitely for the blocking connection to release its lock.