There is a little puzzlement among Asynchronousand Synchronous events, however I believe after reading this article, there will be no place for confusion in your brain, the reason for that I go behind a childlike practice to memorize what is Asynchronous ? and what is Synchronous ?

The same babyish method, I want to share with you.

A for Apple, A for Asynchronous and A for After events, so all Asynchronous events occur after the event, which does not stop the code to execute. All Asynchronous events end with ‘ed’ letters like SiteDeleted, FieldAdded, ItemAdded etc.

Now, let’s talk on the subject of Synchronous events, all Synchronous events  occur before the event, which stop the code to execute. All Synchronous events end with ‘ing’ letters like SiteDeleting, FieldAdding, ItemAdding etc.

SPWebEventReceiver Asynchronous Events

SiteDeleted Occurs after an existing site collection deleted.
WebDeleted Occurs after an existing web site is completely deleted.
WebMoved Occurs after an existing web site has been moved.

SPWebEventReceiver Synchronous Events

SiteDeleting Occurs before an existing site collection is being deleted.
WebDeleting Occurs before an existing web site is deleted.
WebMoving Occurs before an existing web site has been renamed or moved

SPListEventReceiver Asynchronous Methods

FieldAdded Occurs after a field link is added.
FieldDeleted Occurs after a field has been removed from the list.
FieldUpdated Occurs after a field link has been updated

SPListEventReceiver Synchronous Methods

FieldAdding Occurs before a field link is added to a content type.
FieldDeleting Occurs before a field is removed from the list.
FieldUpdating Occurs before a field link is updated

SPItemEventReceiver Asynchronous Methods

ItemAdded Occurs after a new item has been added
ItemAttachmentAdded Occurs after an attachment added to an item.
ItemAttachmentDeleted Occurs after an attachment removed from an item.
ItemCheckedOut Occurs after an item is checked out.
ItemDeleted Occurs after an item is completely deleted.
ItemFileMoved Occurs after a file is moved.
ItemUpdated Occurs after an item is modified/edited.

SPListItemEventReceiver Synchronous Methods

ItemAdding Occurs before a new item is added.
ItemAttachmentAdding Occurs before an attachment is added to an item.
ItemAttachmentDeleting Occurs before an attachment when a user removed from an item.
ItemCheckingIn Occurs before a file is checking-in.
ItemCheckingOut Occurs before an item is checking-out.
ItemDeleting Occurs before an item is completely deleted.
ItemFileMoving Occurs before a file is moved.
ItemUncheckedOut Occurs before an item is unchecked out.
ItemUncheckingOut Before event that occurs when an item is being unchecked out.
ItemUpdating Occurs before an existing item is modified/edited.

SharePoint Foundation 2010 New Events

Microsoft added several new events to SharePoint Foundation 2010 on Site, List and Item level. These fresh events are intended to meet up the requirements and for better elasticity.

SPWebEventReceiver

WebAdding Occurs before a new web site is created.
WebProvisioned Occurs after the web is provisioned.

WebAdding: event arises prior to a fresh web site is created, we can control the website to create or not to create by WebAdding event, then no SharePoint site is created and the provisioning process is not started.

WebProvisioned: event arise after the web is totally provisioned and process has stopped up. WebProvisioned can be configured to control in any synchronous or asynchronous methods.

If user wants to add few webparts to the newly provisioned web we can use this event to meet up the necessity

SPListEventReceiver

ListAdding Occurs before a list is created.
ListAdded Occurs after a list is created.
ListDeleting Occurs before a list is deleted.
ListDeleted Occurs after a list is deleted.

Please follow Catalog of SharePoint Foundation Events for newly added event in SharePoint Foundation 2010