Enough talk about the how and what of meditation, don't you agree? Why do people meditate? What's the goal, what do they want to achieve with it?
Short answer: whatever you like.
Long answer: you can meditate to find peace and rest. Meditation can be employed to calm yourself down, to relax and unwind from the day. Depending on the way you meditate you can also taken on stress. Stress is like a fine layer of dust that falls down on your mind, your nerves, your Self. After a while this thin layer becomes thick, sinks in, and becomes a massive clot of misery that is difficult to get rid of. Using the proper forms of meditation you can use it as a chisel to chop away bits of that stress-blob, and slowly free yourself from it. When you've removed all the stress you keep meditating to prevent stress from getting to you.
You can also meditate to find answers to questions. Meditation lifts you up from the normal level of thinking and worrying. As you ascend from that level, you get a far better overview and insight of the problem you are facing. Since a problem usually is not solved on the level where it originated, this way to deal with a problem is very good as you can approach it with a different, far clearer and cleaner attitude.