Covenants, conditions and restrictions (commonly referred to as CC&Rs) are rules that come along with living in certain communities. If you're looking at a townhome, there's almost certainly one for the property. It's not just the parts of the home that your neighbors can see – a CC&R can specify who can live in your home, whether you have pets, what you're obligated to do if there's a pest infestation, whether you can hang a clothesline outside, and other aspects of your day-to-day life.
While they can limit what you can do with your property, CC&Rs usually have benefits as well. Because of them, condominium complexes and rows of townhouses often look nicer, are safer and maintain higher property values. They can also prevent common neighborhood annoyances. The CC&R can keep your neighbors from blocking your parking space with a dumpster during a months-long construction project, digging a pool that encroaches on your patch of yard or adopting an army of noisy puppies (and then leaving their messes in the landscaping). In other words, pretty much nothing is off the table; it simply depends on the local standards. Read the CC&R documents all the way through before you sign on the dotted line.