It is not difficult to add a friend to your car insurance policy if you need to, but it may not be required, depending on the circumstances. If your friend is only borrowing the car for a day, then all you need to do is notify the insurance company that they are driving the car, but if the vehicle will be on loan or used frequently you should have them added. Your rates may increase, but that will depend on a lot of factors including how long the friend will be using the car, how far they will be driving and their personal driving record.
If your friend lives in the same home, your insurance company probably wants to put them on the policy anyway, just as they would anyone else living in your home such as a parent or sibling. The reason for this is because insurance regard any licensed driver in your home as a potential driver of your car, and listing them prevents trouble arising at a later date. Similarly, you can have a person excluded from your insurance, which means they are never allowed to drive the car and are not covered by your car insurance if they do so.
If you are planning to add a friend to your insurance policy, you can find the best rate quotes by getting online insurance quotes from the Internet. Online quotes are available every day of the year, and many sites will even allow you to get a new policy on the spot, without ever taking time out of your normal routine to go into an insurance office and sign up. Any time you feel that your current insurance is costing you too much, compare it with some online quotes and look for a better deal or more comprehensive coverage plans that better fit your needs.