What are Wait Types in SQL Server ?
There are 3 types of wait types...
Resource Waits - Resource waits occur when a worker requests access to a resource that is not available because that resource is either currently used by another worker or it’s not yet available.
Queue Waits - Queue waits occur when a worker is idle, waiting for work to be assigned.
External Waits - External waits occur when an SQL Server worker is waiting for an external event.