There are numerous ways to backup your Gmail data and deciding which way to go will largely depend on the level of effort you want to put into it. You could simply setup Gmail to forward all your mails to another email account and call it a day, for instance. But there are also a handful of other options that offer a bit more flexibility and convenience.
In this brief guide we've listed a few of them, so you can choose whichever best suits your needs.
Read the complete guide.