Selecting content for a feed

What if some of your site content is secure, or available only to premium subscribers? No problem! We're going to look at a way to filter the content selected for the feed, or, conversely, filter out content that you do not want selected. 

We're going to create three feeds. The first thing we need to decide upon is what content the feed will contain...which means determining the selection criteria. 

One of our feeds is destined for the pet-loving community. It will contain any of our articles related to pets.

Our second feed is for travelers. It will contain any of our articles related to travel.

Finally, our third feed will contain any article that not included in the first two feeds.