There are several different types of squats, which target different muscles. With the front squat, you're able to build your quadriceps. Because the barbell be positioned in front of you, you'll be hitting more of the front muscles of your thighs, than you would for hamstrings or even glutes.
Although the back squat also hits the quad muscles, it doesn't do it as well as what a front squat could.
There are plenty more benefits to the front squat, beside building boulders for thighs. It also helps with mobility and core strength. Try out this exercise with a barbell. If the barbell is too intimidating for you, you can also try front squats with a kettlebell, dumbbells, or just simply use your bodyweight.
Here's How To Barbell Front Squat:
1) Choose a weight that you're comfortable with. If you're unsure, just start with the bar and build the weight up. A normal bar will be 45lbs. You're more than likely going to have to start with a weight much lower than what your barbell back squats numbers are. You can also warm up with body-weight front squats by stretching your arms in front of you for balance and stability.
2) Position the bar in front of your shoulders, or front delts. The bar should be close to your neck. So, it'll actually feel kinda awk. You may either cross your arms, or grab the bar like in the cover photo for this card. Crossing your arms may be easier if you have issues with wrist flexibility. I prefer to cross my arms, for this very reason.
3) Make sure not to drop your elbows. For this squat, you're not sitting back like you would for a low-bar back squat. You will be dropping down instead.
4) Keep a neutral spine. Grab the barbell tight. When squatting, try to go as low as possible, without breaking your neutral position. If you're not familiar with the exercise, or the weight is too heavy, your back might round. You don't want this. Limit your squat depth, if a deeper squat is screwing with your neutral back.
Tip: Squat (Olympic) shoes may help keep a better posture for your squat. You may also try stepping on 10lb plates to help keep your heel a bit elevated. This will also help with posture.