Akeeba Solo / Akeeba Backup is an application which lets you back up, restore and transfer your sites. From its perspective it doesn't care if you are restoring a backup (restore on the same site) or transferring a site (restore on a different site or server). This is what makes it powerful: the same backup can be used to restore a site to its previous state, move the site to a new location or server, or even create perfect clones of a site.
Each backup taken is placed inside a backup archive. A backup archive is a compressed file. The formats supported by Akeeba Solo / Akeeba Backup are JPA (an open source format optimised for fast backups), JPS (like JPA with an added layer of strong encryption to protect the contents against prying eyes) and ZIP (the standard, but much slower, compressed file format).
Each backup archive contains three things:
A copy of all the files of your site
A "dump" (backup copy in SQL format) of your site's database contents
A PHP script used to restore the database "dump" and, optionally, reconfigure your site.
Thus, each backup archive is self-contained: it has everything you need to create a copy of your site on the same or even an entirely different server. That said, the backup archive does NOT include a few things which some people might mistakenly believe are part of their site:
Your hosting account setup information, such as domain names, DNS records etc. This also includes email accounts set up on your server, including an archive of email messages. Accessing this information requires special access privileges which are usually not granted to PHP applications, such as Akeeba Solo, by your host for security reasons. We recommend against trying to include this information in the backup. You are unlikely to succeed and you will be actively degrading the security of your hosting account.
Files and folders outside your web site's root directory. You can optionally include them in the backup using the Off-site Directories Inclusion feature.
Database tables belonging to a different database than the one being used by your site. You can optionally include them in the backup using the Multiple Databases Definitions feature.
Akeeba Solo / Akeeba Backup can backup and restore different sites using one or more backup profiles. Each backup profile is a collection of configuration settings which define a specific way to backup portions or the entirety of a site. You can of course use multiple backup profiles for each individual site. This is useful when you want to be able, for example, to take a full site backup but also have the option to grab a quick backup of just a few frequently changing files and database tables.
Backups by default only run manually, through the application, whenever you click on the Backup Now button. You can automate backups in many different ways. It is worth noting that you need an external trigger for the backups, be it the CRON job scheduling of your server or a third party service. PHP is really bad at triggering lengthy, resource intensive procedures like full site backups as part of the process of generating a site of your page.
Transfer to external servers or cloud storage is part of archive post-processing. This is something you can configure in the Configuration page of the application.