What is Workflow?
Workflow is the ability to have moderation states for content and be able to move through those moderation states. In Drupal, the content types basic pages, articles, events, local galleria, and people profiles all have workflow enabled. Custom blocks also have workflow enabled. Each page and block can be saved as "draft", "published", or "in review". Once something is published, there is also an "archived" option.
Understanding Moderation States
A brand new page from a content type or a brand new custom block will be set in draft mode by default. When it is the very first draft, this content will not be viewable by visitors; only authenticated users who edit the site will be able to view the page or block, until published. Subsequent drafts are creating a pending revision. When switching from published to draft, your existing content stays published, and the newest draft will be only visible to authenticated users until that draft is published.
You can save or change current state "Draft" to "Draft", "Published" or "In review". You can change to "Draft" from "Published" or "Archived" states.
When a page or block is published, it is viewable to visitors. It also means that the page is crawl-able by search engines (unless there are robot limitations set). Pages should only be saved as published when they are ready to be made live. A page or block will remain published, even if the page or block is revised and then changed to "draft". The revisions won't be live yet until changed to "published" once again.
You can save or change current state "Published" to "Draft" or "Archived". You can change to "Published" from "Draft", and "In Review".
In Review State
This state is similar to draft. Once changes have been made to a page it can be set to "In Review". This won't auto create a workflow or set off an email to anyone in particular. The content list will show that this page has a state of "In Review". If someone needs to act on this state, it will be be easier to find these pages with this set state.
The archived state is the unpublished state. If you wish to un-publish existing content you will need to select the "Archived" state. This will keep the page on your site so that editors can still access the content but visitors will now be directed to the 403 error page.
Archived state can only be reached if the page is set as "Published".