Not only does an online service give you more options in one place than you would otherwise have, but you also get to connect with and learn a little about prospective partners before you decide whether you want to know more about them or not; in the real world you may sometimes waste hours trying to get to know a person, only to find out that you have no common interests.
Internet dating also makes it easier for you to find someone who is looking for the same thing that you are relationship-wise.
Often first dates are stiff and uncomfortable because both parties are unsure of what to expect but in online dating you are able to talk to prospective dates before you meet them so you feel more at ease when you do meet for the first time; also there are a lot of people who are more at ease typing than speaking so they are able to express themselves better in an online conversation as opposed to a face to face one.
Online dating also allows you to meet people all around the world that you would not otherwise be able to connect with.
Too often in face to face dating relationships fail because one partner is only looking to have a little fun while the other party wants a long-term commitment; online dating eliminates this problem as you can use a service that caters to the kind of relationship you are looking for so you know what you are getting before you commit yourself to a relationship.