Bitcoin mining has grown from a handful of early enthusiasts into a cottage industry, into an industrial-level venture. The easy money was scooped out a long time ago and what remains is buried under the cryptographic equivalent of tons of hard rock. Today, bitcoin mining is big business, and technology is rapidly advancing to increase efficiency and push more and more miners out of the market.

Mining bitcoins today is not the same thing as mining bitcoins a few years ago. Back then, you could mine hundreds of coins a day with just one or two computers and they were easy to sell. Today, bitcoin-mining computer rigs often consist of multiple high-speed graphic processors (ASICs) that run hot enough to keep homes and offices warm through winter — they're built for speed, not for efficiency. Even if your home isn't heated by burning excess heat, there's always a nearby server room where it can be put to good use.

But this doesn't mean you need an entire room full of hardware to get started in bitcoin mining; far from it. The hash rate of a mining computer is measured in mega hashes per second (MH/s). It refers to how many math calculations your hardware can perform every second as it tries to crack the bitcoin code.

For example, a typical CPU achieves a hash rate of about 20 MH/s. In other words, this CPU could calculate 20 million hashes per second. If you have a more powerful GPU that cranks out 1,000 MH/s, then it could do 1 billion hashes in one second! This is not even close to the number-crunching power available on high-end devices with multiple graphics cards and ASICs.

What Is the Hash Rate?

Mining, in a nutshell, is the process of turning computing power into actual Bitcoins. That seems simple enough, but there is considerable work involved. The miner has to count the value of all transactions going across the entire Bitcoin network and then perform a "proof-of-work" that involves calculating an extremely hard math problem with the use of cryptographic hash functions.
The solution to this math puzzle verifies all transaction blocks and gives everyone trust that it's genuine - because there's no way for anyone to be able to fake it. That means no one can spend their cryptocurrency twice or counterfeit it by copying past transactions in the blockchain. To solve this problem, miners have what's called a hash rate — which measures how fast they can calculate hashes.
The hash rate is also the measuring stick for the amount of cryptocurrency that can be mined in a certain period (usually daily). The more miners there are, the higher the network hash rate is and the less profitable mining becomes because it's harder to create new blocks (and earn bitcoin). It takes large quantities of hardware, electricity, space, and cooling to mine bitcoins; which means even if you have cheap or free electricity it could take years before you see any return on your investment.
To measure this rate, we use an advanced performance measurement called "hash per second" or just "hash rate". Each unit measures how many attempts at solving a Bitcoin block a miner can perform every, expressed in hashes per second.
To figure out the hash rate of your Bitcoin mining hardware, you will need to look at two things.
For new Bitcoin miners, this is arguably the most important question to answer. Most modern hardware measures its power in Th/s (trillion hashes per second). The more TH/s you have, the more likely you are to solve a transaction block and earn Bitcoin (consider it like winning a lottery). Mining profitability calculators show results in LTC/day (Litecoins per day), which is then converted into BTC/day by applying the current exchange rate.

How Is Hash Rate Calculated?

Since mining difficulty is constantly increasing and the number of bitcoins rewarded also changes per block, you can calculate your expected payout using a bitcoin mining calculator.
There are many calculators out there that will do all of the heavy liftings for you after asking about your hardware and electricity costs. This way, the only thing left to do is sit back and watch as your digital wallet fills with freshly minted coins. As long as you pick a reputable service then there isn't much risk involved at all on your part. The question remains: what should I buy?
This one calculates how many bitcoins you can expect to mine based on the current speed of your computer and the total network hash rate: Bitcoin Mining Calculator.
If you want to join a mining pool then this website will show you which pools are currently the most popular and the most profitable: Bitcoin Network Hash Rate Distribution.
It's all very exciting but what do those MH/s mean? For example, 600KH/s is equivalent to six hundred thousand (6 x 100.000) hashes per second. If your hardware can do 600 billion hashes per second, then it would be around 450MH/s (600KH/s x 1). The following section explains how bitcoin mining works and how it's tied into bitcoin security.
Bitcoin mining is intentionally designed to be resource-intensive and difficult so that the number of blocks found each day by miners remains steady. Individual blocks must contain proof of work to be considered valid. This proof of work is verified by other Bitcoin nodes each time they receive a block. Bitcoin uses the proof-of-work function.
The primary purpose of mining is to allow Bitcoin nodes to reach a secure, tamper-resistant consensus. Mining is also the mechanism used to introduce Bitcoins into the system: Miners are paid any transaction fees as well as a "subsidy" of newly created coins. This both serves the purpose of disseminating new coins in a decentralized manner as well as motivating people to provide security for the system.
Bitcoin mining is so-called because it resembles the mining of other commodities: it requires exertion and it slowly makes new currency available at a rate that resembles the rate at which commodities like gold are mined from the ground.
It must be trivial to check whether data satisfies said requirements. Producing a proof of work can be a random process with low probability so that a lot of trial and error is required on average before a valid proof of work is generated. Bitcoin uses the Hashcash proof of work system.