Having your Joomla site running fine is great, but as with any data it is important to have backups. The same applies to Joomla based web sites.
Your host should have a backup option in place, maybe 14 days of archived daily backups. However this is often inadequate and your should have an additional backup option.
Akeeba provide an excellent alternative including a free version.
The following should be considered with any backup solution.
- Automate backups regularly to off site storage.
- Run manual backup prior to a site change for example 3rd party addon or upgrade
- Run backup once again once site changes have been made
- Manual backups to be copied off site