I’ve been going through the list of tables on my Drupal site in prep to convert an existing single-site to a multi-site with a shared database. However, I haven’t found any reference that illuminates the general purpose of the tables. I’ve tried to put together at least a preliminary list here. I share it in hopes that someone else might find it useful, but it is not normative or complete.

access

User. This is the table used by the “Access Rules” section for banning usernames, IPs, etc.

accesslog

Statistics. This stores the accesslog if Drupal is collecting statistics.

aggregator_category

Aggregator. Store the categories feeds may belong to.

aggregator_category_feed

Aggregator. Links feeds to categories.

aggregator_category_item

Aggregator. Links feed items to categories.

aggregator_feed

Aggregator. Store the feeds that the Aggregator module pulls from.

aggregator_item

Aggregator. Store the items that the Aggregator module has pulled for the various configured feeds.

authmap

User. This stores a map to the authentication module used to authentication each user in the database.

blocks

Block. This stores information about blocks provided by every module installed, including custom blocks.

blocks_role

Block. Stores the roles permitted to view blocks in the system.

boxes

Block. Administrator created blocks.

cache

System. The general cache of data, used by many modules.

cache_filter

System. I have no idea what this table is used for.

cache_menu

System. I have no idea what this table is used for.

cache_page

System. I have no idea what this table is used for.

cache_views

Views. Used to cache information related to views.

client

Drupal. Used to record Drupal client sites. I believe this is the list of sites that others have logged in from if you use the Drupal module.

client_system

Drupal. I’m not exactly certain what this table is for.

comments

Comment. Stores all comments made on your Drupal site.

contact

Contact. Stores the emails sent via a contact form.

files

Upload. Stores information about files uploaded via the file upload module (and used by some other modules too).

file_revisions

Upload. Associated file revisions with node revisions allowing different node revisions to have different versions of a file associated with them.

filters

Filter. Stores information about the body content filters used in your install.

filter_formats

Filter. Associates filter formats and settings with a body content filter.

flood

Watchdog. Used to detect floods from requests coming from a set.

forum

Forum. Used to link forum posts with the forum topic.

history

Node. Used to track which nodes are read/unread.

locales_meta

Locale. Something to do with language translation.

locales_source

Locale. Something to do with language translation.

locales_target

Locale. Something to do with language translation.

menu

Menu. Storage of menu module customizations.

node

Node. The main table for storing general node information, including the title, node number, dates, workflow state, but it does not store most of the actual content.

node_access

Node. Storage of per-node access permissions.

node_comment_statistics

Comment. Notes certain statistics related to the number of comments and how recently comments have been made on a node.

node_counter

Statistics. Records the view count for each node.

node_revisions

Node. Stores information about node revisions, including the main content of the node.

node_type

Node. Stores information about the custom node types.

permission

User. Stores the permissions that have been assigned to each role.

poll

Poll. Extra information associated with poll nodes.

poll_choices

Poll. Associates the available choices with a poll node.

poll_votes

Poll. Votes by visitors on a poll node.

profile_fields

Profile. Definitions of available profile fields.

profile_values

Profile. Profile field values associated with a particular user.

role

User. Assigns role IDs and names to all the roles in the system.

search_dataset

Search. Something to do with search.

search_index

Search. The search index.

search_total

Search. The number of times a given word appears on the site.

sequences

System. The current counter for each of the sequence IDs.

sessions

User. User session tracking data stored in the database.

system

System. Information about installed modules.

term_access

Taxonomy Access Control. Access control per category.

term_access_defaults

Taxonomy Access Control. Access control per vocabulary.

term_data

Taxonomy. Definition of taxonomy terms.

term_hierarchy

Taxonomy. List of parent terms for each taxonomy term.

term_node

Taxonomy. Table linking taxonomy terms to nodes.

term_relation

Taxonomy. Relationships between taxonomy terms.

term_synonym

Taxonomy. Alternative names for a taxonomy term.

tinymce_role

TinyMCE WYSIWYG Editor. Roles assigned to use TinyMCE profiles.

tinymce_settings

TinyMCE WYSIWYG Editor. Definition of TinyMCE profiles.

url_alias

Path. Path aliases recorded to nodes.

users

User. User records.

users_roles

User. Link table between users and roles.

variable

System. Administrative settings and other site-wide variables.

view_argument

Views. Definition of arguments to a view.

view_exposed_filter

Views. Definition of exposed filters in a view.

view_filter

Views. Definition of filters in a view.

view_sort

Views. Definition of sorting in a view.

view_tablefield

Views. Something to do with the views plugin.

view_view

Views. Basic information about a view.

vocabulary

Taxonomy. Definition of taxonomy vocabularies.

vocabulary_node_types

Taxonomy. Associates vocabularies with node types.

watchdog

Watchdog. Records watchdog log entries.