Bitcoin FAQ: Where do Bitcoins come from, and can I get rich by mining them?

The miner that finds the right answer to these calculations is given a reward for their hard work: 25 Bitcoins. This process is called solving the block. Once the block has been solved, the process restarts, and the miners start looking for the next solution. This process runs repeatedly, with an average of one block being solved (and thus 25 Bitcoins being created) every 10 minutes or so. You can see the blocks being solved here.
Can I get rich mining Bitcoins?
The short answer is No, unless you started some time ago. The long answer is more complicated. Solving an odd math puzzle might sound like money for nothing, but there is a real cost involved: the cost of the computers that do the solving, and the electricity they use. When you start running your computers at high speed 24/7, your electricity bill goes up.
A puzzle that gets harder the more you try and solve it: from kH/S to MH/s to GH/s.
That sounds pretty simple so far: computers are good at crunching numbers, and an average computer can run several thousand of these calculations (called hashes) a second. But there is a catch: to restrict the flow of new Bitcoins, the difficulty of solving the block to find the Bitcoins changes regularly. One of the factors that controls this change is how much computing power was used to solve the last few blocks. This means that the more computing power people throw at the problem, the harder it gets. This happens by increasing the number of consecutive zeroes that are required to solve the block. This has created a cycle that makes Bitcoin mining unprofitable for most users.
When Bitcoin started out, most people were using the CPU of their computer to run the software that did the math. These CPUs could do between 2 and 5 thousand hashes a second, so the typical speed was about 2 to 5kH/s (kilohashes per second). However, in 2010, miners realized that these calculations could be done by another part of the computer, the Graphics Processing Unit (GPU) used to create the graphics for computer games. With some tweaking, the GPU of a high-end graphics card could run these calculations much faster, because they aren’t that different to the ones used to render games. A high-end graphics card could do upwards of 500,000 hashes a second, or 500 kH/s (kiloHashes per second). If you put multiple graphics cards into one computer, each card could run these calculations separately, so you started to see people with miners that could do over a million hashes a second, or 1 MH/s (1 MegaHash per second). Shortly after that, several companies adapted Field-Programmable Gate Array (FPGA) chips to run the task, which had similar speeds as GPUs, but used less power.They then sold these devices to Bitcoin users, who ran them to mine more Bitcoins.
This lead to the rise of so-called mining farms, where Bitcoin users would buy multiple computers, each with multiple graphics cards, and set them all running the software that crunches the numbers, looking for Bitcoins.