You can print pictures at home on a photo printer, or you can send them to a printing service. Both options have some pros and cons. If you buy a printer, you can print your pictures right away. Many printers are portable, so you can take them with you on vacation and print photos as you go. But the cost of the printer, ink and paper can add up -- in general, this is an expensive way to print your photos.
Most of the time, using a professional printing service is a more economical option. You can make standard-sized prints for a few cents each and very large prints for a few dollars. Typically, you sign up for a free account, upload the photos you want to print, and place your order. Sometimes, you can take CDs of images to an in-store kiosk and place your order there.
Using a professional service is generally cheaper than buying your own printer, and your prints will probably be better quality. However, uploading the pictures can take time, since you'll want to send full-sized, high-resolution pictures. You'll also have to wait a few days for your prints to arrive.