Understanding the database structure of wordpress is your first step on the road to become a wordpress developer. I hope this information can be useful to you.
The first, WordPress database is fairly simple, including only 11 tables but can be used for many different types of websites. Here we keep the default WordPress table prefix is wp_ . Of course, you can change this prefix if you want, in installation process 
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1/ wp_options 
Save the configuration information website, the fixed information, little changed. 
2/ wp_posts 
Containing the post, page, attachment, nav_menu_item,... Generally wp_posts table will contain the data type "single" as products, books,...etc. 
3/ wp_postmeta 
WordPress gives us wp_postmeta table to store additional information is not limited. For example, for more information about the short description for the post, I added the wp_postmeta table as follows: post_id = [id of the post], meta_key = 'description', meta_value = [paragraph description] and so on. 
4/ wp_comments 
Save the comment, post comment 
5/ wp_commentmeta 
More information of comments 
6/ wp_terms 
Save id, name, slug, the group's taxonomy (category, tag, menu, ...).. Generally save the "container" as trademarks, cities,...etc 
7/ wp_term_taxonomy 
Save the information of the term: What type (category, tag, menu, ...), description, parent term (the term the public), the number of items contained in it. 
8/ wp_term_relationships 
Table relationships between post and taxonomy 
9/ wp_users 
Save user information 
10/ wp_usermeta 
Save more user information 
11/ wp_links 
Save the link
Hope it helps!
Alex
