Remote event receivers handle events that occur on an item in the app, such as a list, a list item, or a web. Visual Studio 2012 provides a template to create a remote event receiver.
In SharePoint 2010, event receivers handle events that occur on SharePoint lists, sites, and other SharePoint objects by running the code on the SharePoint server (either full-trust or in a sandbox). This type of event receiver still exists in SharePoint 2013. However, SharePoint 2013 also supports remote event receivers in which the code that runs when the event is triggered is hosted by a web service. This means that if you register a remote event receiver, you also need to tell SharePoint which web service to invoke.
Three categories of events in provider-hosted apps:
- List events, such as the adding or deleting of a list on a website.
- List item events, such as the editing of an item in a list.
- App events, such as the installation of an app.
There are two kinds of events:
Before events are triggered before the SharePoint infrastructure does any of it's own handling of the event (including committing changes to the content database). In SharePoint custom before event handlers always execute synchronously.
Example, if your handler for the ItemAdding event cancels the event, the ItemAdded event, which normally comes later, is not triggered.
After events are triggered after the SharePoint infrastructure does any of it's own handling of the event. In SharePoint, remote after event handlers, for list and list item events, always execute asynchronously.
Thanks for learning my blogs.
reference:msdn