Here's some decent references for events
A remote event is useful for client-server/server-client communications
http://wiki.roblox.com/index.php?title=Remote_Events_and_Functions
A bindable event is useful for server-server communications
http://wiki.roblox.com/index.php?title=API:Class/BindableEvent&redirect=no
Scripting helpers even made their own guide(s)
https://scriptinghelpers.org/guides/server-client-relationship-in-roblox
https://scriptinghelpers.org/guides/how-to-use-remoteevents-properly