I purposely use the word "WHAT" because I do not want to confuse non-techies.
Particularly the the term "files" when discussing about WordPress backup.
To avoid further confusion, here I do not talk about how to back up.
This post is solely about what you need to back up from your WordPress for safe keeping.
What To Back Up From WordPress
Your WordPress site is made up of: Website Files and Database.
These are the three Website Files and one Database which you need to back up:
1. WordPress Core
2. Wp-content Folder
3. WordPress Configuration Files
4. Database
The first three are termed as: Website Files.
They (WordPress core, theme, plugin files, etc.) have to do with the look and feel of your site.
The forth one is called: Database.
It stores all of the content (articles, pictures, video clips, etc.) you published in your website.
Now let's go through one by one.
First we talk about the three Website Files:
WordPress Core
When you install WordPress, you are installing a collection of files and that is what they call "WordPress core".
The WordPress core files make up the appearance and functionality of your WordPress site.
These files can be seen in the root folder: wp-includes and wp-admin folder.
You normally would never make any changes to these files, so they remain the same on all WordPress sites.
You just back up these files once and you don’t always need to backup these files.
You can always get fresh copies of these files from WordPress.org website.
Wp-content Folder
The folder is named as: wp-content.
Basically anything you upload to your WordPress site gets store up here.
It includes your themes, plugins, uploaded files, and images.
If you know what plugins and theme you had installed on your WordPress site, then you can always get fresh copies of these plugins and themes from their sources.
In that case, you don’t need to backup plugins and themes folders.
But if you have a customized theme (means you made changes to its original design), then you definitely need to back up these folders.
As all your images are in /wp-content/uploads folder, and if you lose this folder, then you will not get them back for good.
So, it is a must to back up this folder.
WordPress Configuration Files
Without this configuration file, your WordPress website will not function.
It contains your connection details.
The two important WordPress configuration files you need to back up are:
wp-config.php file
.htaccess file
The wp-config.php file is generated during the installation process.
It stores your database information.
Without this information, your WordPress website will not work, and you will get the 'error establishing database connection' error.
Now, let's talk about the forth one called Database.
WordPress Database
WordPress stores all the data in a MySQL database.
This is where all your posts, pages, users, comments, categories, links and everything else is stored.
If your database gets deleted or corrupted, you will lose everything you have written or published.
This is the most frequently updated part of your WordPress site.
In other words, you must back up database more frequently.
So these are the four WordPress main content which you must back up, so you can use it to restore your WordPress site.
Related Topics:
Free BackWPup Plugin To Backup WordPress Site To Dropbox
How To Back Up WordPress Database With phpMyAdmin
How To Partial Backup WordPress Site With Web Host Backup Tool