Each Stack Exchange site has a weekly email newsletter.
What is in the newsletter? Who composes them and selects what is included? How do I subscribe and unsubscribe to a newsletter?
What is the weekly newsletter, and who writes them?
The newsletter is simply an email which is mailed out to everyone opted into it every week. It is specifically designed to be useful to those users who enjoy a site, but don't check in all that often and would like to stay in the loop. All the content in each newsletter is automatically selected by the system when the newsletter is generated.
Each site on the network has its own newsletter and each newsletter includes a briefly summary of:
They may also occasionally contain important announcements from Stack Exchange staff and moderators, such as information about ongoing elections.
What does it look like?
If you'd like to take a peek at what the weekly newsletter will look like before you subscribe, the easiest way to do that is to visit the newsletters page. This will list every site and to the right you will see links for subscribe and preview. Click the preview link to be taken to a page which displays the last newsletter that was sent out.
How do I subscribe to the newsletter?
How do I unsubscribe from a newsletter?
Each newsletter you receive will have a link at the very bottom of the email titled "Unsubscribe from this newsletter" - this is by far the easiest way to cancel your subscription to it.
If you would like to manage multiple subscriptions at a time, you can do so by visiting your profile at stackexchange.com and then clicking on the "subscriptions" tab of your profile (only visible to you). This tab will list all of your current email subscriptions for both tag filters and newsletter, and includes links to unsubscribe from each of them right there on the page.