SQL Server Lock Modes

Depending on the type of access requested, SQL Server uses different lock modes while locking resources:
• Shared (S)
• Update (U)
• Exclusive (X)
• Intent:
       • Intent Shared (IS)
       • Intent Exclusive (IX)
       • Shared with Intent Exclusive (SIX)
• Schema:
      • Schema Modification (Sch-M)
      • Schema Stability (Sch-S)
      • Bulk Update (BU)
      • Key-Range