Most television sets you can buy today are HDTV capable, and will enable you watch great high def pictures at home. There are several ways to receive HDTV signals - too many for the scope of this article, so please search elsewhere on this site if you need to find that information out - one way might be using some sort of set top box, that is capable of receiving HDTV signals and is hooked up to an antenna.
If this is the case for you and you're not sure whether it's best to use an outdoor or an indoor hdtv antenna, then please keep reading ...
Indoor HDTV antenna
Let's start with the main advantage for using an indoor HDTV antenna - convenience. Those of you that live in apartments or properties where there is no private area to install an outdoor antenna may find that it is an absolute necessity to have the flexibility an Indoor HDTV antenna will give you.
The major disadvantage of an indoor hdtv antenna is, needless to say, the reception quality. Unless you live in a metropolitan area or are reasonably near a television broadcasting tower, you will probably not receive a good enough signal to watch comfortably.
This can be helped by using an amplified indoor HDTV antenna, which will boost the signal, but it still might not provide enough of a signal if you are fairly far from a broadcasting tower.
Outdoor HDTV Antenna
So, the best option, if you can accomodate it, is to get yourself a HDTV outdoor antenna. If you can place one outdoors you will get a much better quality service than by using an indoor HDTV antenna. There is also a bigger range of outdoor antennas, including different direction types and sizes, that should help you with your situation, but make sure you do some research with your neighbors and any other locals who might have an antenna already set up to find out what type you will likely need.
If you are in the US, you may want to check the Consumer Electronics Association antenna guide to help you find out the strength of TV signals in your location. This can be a big help, and will likely save you money by enabling you to make the correct choice straight away without having to first spend money on an indoor HDTV antenna only to find out that it can't receive a strong enough signal. Be wary that this guide will not cover indoor HDTV antennas specifically, but will give you a general idea of signal strenth and will tell you immediately if you will definitely need an outdoor antenna.
In some cases you can also get an outdoor / indoor HDTV antenna which will give you the best of both worlds, so have a look out for those if you're undecided or living at a temporary address.
Bottom line is: Get yourself an outoor antenna. If you have limited space and an outdoor antenna is out of the question, then do some research. Find out whether an indoor hdtv antenna is going to work for you before making any purchase.
Well, I hope this helped.