Mysql events table

I am trying to create a script to backup all mysql databases.

This is the command that I am trying :

sudo mysqldump -u user -ppassword --all-databases > /tmp/all-database.sql

And this is the error that I've got:

-- Warning: Skipping the data of table mysql.event. Specify the --events option explicitly.

I added --events and it works.

Why should I add it ? What's special with this table ?