Akeeba Backup is the industry standard backup solution for Joomla and is probably the most important addition to a standard install.
Akeeba Backup backs up the database and all the files in your web space into one compressed file. This makes it easy to copy the backup to your local machine or elsewhere.
Restoring a website is also straightforward by uploading the backup file to your web space and uploading and running Akeeba Kickstart, another utility supplied by Akeeba.
Paying a subscription is recommended as this entitles you to log support requests with the the developer and ensures he has an income to continue developing and supporting this excellent and essential extension.