Item Checked Out – This occurs after an item is checked out.
In this case, there is a flexibility of cancelling the event on some conditions so that the event that gets initiated will not occur.
There are basically two types of event receivers: Synchronous and Asynchronous event receivers.
Synchronous event receivers are also known as ‘Before’ event receivers.
Item Attachment Deleting – This occurs while an attachment is being removed from an item.
Item Checked In – This occurs after an item is checked in.