Final answer:
A Shared lock is the type of lock that allows users to view data in a table but prevents the alteration of the table's structure. this ensures data integrity and consistency in multi-user database environments.
Step-by-step explanation:
The type of lock described in the question is a Shared lock. a Shared lock allows concurrent users to view the data stored in a database table, but prevents them from making any changes to the table's structure which includes alterations to the schema such as adding, dropping, or altering columns. this level of access is particularly useful in multi-user database environments where data integrity is vital and it helps maintain consistency as users can still query the table for reports or analysis but cannot modify its design while the lock is in place.