If you have a WordPress website then you need to make sure you backup the website data just incase something goes wrong.
What to Backup in WordPress
WordPress is made up of the core files and a database. So you need to backup everything. To Backup the WordPress Core Installation you will need an FTP client. If you take a copy of everything you will be copying:-
1. WordPress Core Installation Files
2. WordPress Plugins Files
3. WordPress Themes Files
4. Images and additional Files.
6. .htaccess file
7. Robots file
8. Sitemap.xml file
Taking a full backup ensures you have everything you need to rebuild WordPress and once you have these files safe you can also use them if you get hacked to quickly erase what the hackers changed.
You now need to backup the complete database using something like phpMyAdmin. WordPress provide an export facility to export the content of the website but this is not a complete backup of the data.