If you're advertising on Facebook (or even if you think you might do that in the future sometime), you should have the Facebook remarketing pixel code on your website. It keeps track of who visits your website so that you can send ads specifically to them. This is a great way to spend ad dollars because you're hitting traffic that is interested in what you do. You can bring them back with a special offer or new article.
Facebook has announced that they're changing the remarketing code and you want to make sure you update it by the end of 2016:
What's happening to the conversion pixel? (facebook.com)
To best position your business for success, we made one Facebook pixel that combines both the conversion tracking pixel and the Custom Audience pixels, and enables us to build more solutions for you going forward. To make sure you're using the best tools possible, we're removing the conversion tracking pixel in early 2017. For conversion tracking, optimization, and remarketing, we recommend upgrading to the Facebook pixel at your earliest convenience.
If you need help doing this, our Website Maintenance team is ready to help!