Free weights are the simplest and most cost effective pieces of equipment for the beginning muscle builder.
Free weights consist of barbells, dumbbells and weight plates. They are called free weights because they have no cables, pins or pulleys.
Available as normal weights or Olympic weights, be advised that Olympic weights are generally much more costly. The Olympic bar is also thicker at the ends to accommodate the larger hole present in Olympic weight plates.

Barbells come in all shapes and sizes. They consist of a bar that is usually 4' to 7' in length and can weigh from 20 to 45 pounds.
The Olympic bar that you find in most gyms is 45 pounds. This is the one you find on the squat rack and bench press. So, if you use this bar and add a 45-pound plate to each side, you're bench pressing 135 pounds.

Varying weights are attached to the ends of the bar. The weights are attached using collars or sleeves. You can find barbells in a fixed collar design.
This prevents the weights from sliding off the end of the bar, but they are limiting as the weights cannot be removed. With adjustable collars you can add and remove weights to suit your own purposes.

The longer 7' bar that is generally referred to as an Olympic bar can hold 500 to 1500 pounds. As mentioned, these are usually more costly. There are also other Olympic specialty bars available that are designed for specific purposes such as biceps and triceps.

The weight plates that fit the ends of the bar come in standard increments of:

2 1/2 pounds 5 pounds 10 pounds 25 pounds 50 pounds
If you stick with cast iron weights you are pretty much guaranteed that the weights will remain constant over time as opposed to those that are plastic encased or other metals that could warp over time.

If planning to go with the home gym, sticking with standard weights is probably best for you. One of the advantages is that you can find standard weights available as a package that will include your bars, weights and collars. Most standard weight packages also come with dumbbells.

You will also need to have a weight bench. There are varying types of benches. You can find adjustable types that you can set for different inclines. This is a good buy because by adjusting the incline or decline, you can create a number of different exercises to work out different muscle groups.
If you are lacking the money to join a gym, you can set yourself up with everything you need, just by getting some dumbbells, barbells, and a bench. Total cost can be less than $200.

Or, if it's more convenient to work out at home, it's simple to set up an effective gym right in your basement.
Free weights are also effective than machines when it comes to building muscle and increasing your strengh. That's because you have to do all the work and balance all the weight yourself when using free weights.

With machines, much of the work is being done for you. You just have to lift it up and down. As a result, you use less intensity and less overload than with free weights.

Less overload and intensity means less muscle building possibilities.
So don't worry if you can't make it to a gym or if you don't have the money to get certain machines for your home.
When it comes to building muscle, nothing beats a good set of free weights.

http://www.articlesbase.com/fitness-articles/free-weights-are-best-for-building-muscle-9500.html