Hello,
this is the fifth posting.
Q: Why should I consider a backup?
On my static web sites a backup is easy. I create a *.tar file and copy it to another disk. Done. With a WordPress site I have to save some files and (of course) the database.
I found this documentation: Backup einer WordPress Installation 
This documentation mentions a WordPress Plugin: WP-DB-Backup 
The installation was fast and easy, I only had to set the permission of the backup directory.
A: I should consider a backup because the installation of a backup plugin is easy. Starting all over again is a lot of work. Not to mention the time I spend to create the postings and the pictures.
Bye, Tore