There have been frequent incidences of bloggers accidentally deleting their blogs or having Blogger deleted their blogs, etc., so it is good practice to backup your blog so that you can restore it when such calamities happened. Previously we had to use Blog Collector to backup blog. However, Blog Collector had its limitations plus restoring the blog is tedious. Furthermore, Blog Collector only backup text, it does not backup links, embedded content like videos or music players, comments and photos. (note: uploaded photos are hosted at Picassa Web Album, so if your Picassa Web Album account is deleted, those photos will be lost)
Now that Blogger had introduced import blog and export blog, backing up and restoring your blog is very easy. Furthermore, links, embedded content, comments and photos (Update: I think photos may not be restored) is also easily backed up and restored with just a couple of clicks.
To backup your blog, sign into Blogger Dashboard, go to Settings > Basic and you will see 3 links: import blog, export blog, delete blog.
Update: If you are using the New Blogger UI (User Interface), the tabs are in a drop-down menu and "Export"/"Import" is at Dashboard > Settings > Other:
Click export blog and Bloger will create an xml file for you to save into your computer. You would be well advised to save the xml file with a suitable file name and/or in a folder which will enable you to not only easily locate it when needed, but also to distinguish it from a backup template xml file because both are xml files and both will have identical icon
If something drastic happened to your blog, you can similarly go to SETTINGS > BASIC, but this time click import blog, click BROWSE and browse to your exported xml file, complete the captcha (word verification), select whether to automatically publish all imported posts or not, then just click Import blog.
Now a note on the option to automatically publish all imported posts and the possibility of triggering Blogger's bot to mark the imported blog as a spam blog. If you are worried, then you should not tick the box for all imported posts to be published automatically. You will then get a list of imported posts, after which you can publish the posts in batches by ticking some posts and then clicking PUBLISH:
I have tested importing and simultaneously 400+ posts and the test blog was not marked as a spam blog. However, I do not know if you do that you will be as lucky as before I import and publish so many posts simultaneously, I added a noindex meta tag to the template.
This import export features can also be used to export your Blogger blog to other blogging platform like Wordpress, Live Journal, etc., or to import blogs from Wordpress, etc., into your Blogger blog.
Stuff for bloggers