One of the most important factors in the look of a room is the carpet. You can completely change the look of a room just by changing the carpet. More importantly however is the fact that almost all of the other decorating decisions that you will make will be based on the carpet. Since it can be a hassle to change most people will paint the room and choose their furniture so that it matches the look of the carpet.
The main role that carpet plays in interior design is that it largely determines the color of the room. You are going to want to make sure that you paint the walls in a color that matches the carpet. Obviously you can go the other way as well and change the carpet to match the color of the walls but since it is much easier to paint a room than it is to put in new carpet most people will go with the first option. This is also why most people choose a fairly neutral color for their carpet, it gives them greater flexibility when it comes to the color of the walls.
In addition you are going to want to make sure that the furniture and the accessories that you put in the room goes with the carpet. Again this is one of those cases where you can always change the carpet to match the furniture but most people will do the opposite. As a result the carpet usually ends up becoming the defining factor in what the room ultimately looks like. Everything else is based on making sure that it goes with the carpet that you have in the room.
Because of the fact that all of your other decorating decisions are based on what the carpet looks like you are going to want to make sure that you get just the right carpet. This can be a major decision since it is not all that easy to change after the fact. Most people go with a fairly neutral color specifically because it does give them more decorating options, however if you know what you want to the room to look like there is no reason that you have to, you really can pick any color or design that you want.
One thing to keep in mind when you are choosing a carpet is that you want to make sure that you pick one that is practical. It is all well and good to choose a carpet that looks good but if you choose a really plush carpet or one that has a really light color you are going to find that looking after it is a nightmare. Therefore you are going to have to find that trade off between a carpet that looks good and one that is easy to maintain. Inevitably there will be some compromise here but it is much more practical than having a carpet that you can't walk on.
http://www.cagen.org/role-of-carpet-in-interior-design.php
