A fundamental component of SQL Server is locking and locks. Locks within SQL Server are critical to the proper functioning of the database and the integrity of the data within the database. The presence of locks does not inherently mean there is a problem. In no way should locking within SQL Server be considered a monster, though locks may often times be misconstrued in that light.
This is an introductory-level discussion, so it doesn’t include optimistic concurrency or snapshot/RCSI, but if you’re unfamiliar with pessimistic concurrency, this is a good place to start.