Mining
The Nexa mining process seeks to alter a proposed block until its hash, when interpreted an a number, is below a calculated target.
The [block header](../blocks/block.md#block-header is modified in two ways to achieve a new hash.
Primarily, the nonce field is modified and can take any of its 2128 possible values.
In addition, the block timestamp is also updated occasionally to ensure that it remains reasonably current.
As the nonce is rapidly and systematically changed, and the resulting block hash rapidly changes to seemingly random values each time, there is an increasing likelihood that one of the hashes will be below the specified target. Once such a hash is found, the block is then broadcast to the network in hopes that no one else found a suitable block in the passing time.
Types of Mining
Due to the various incentives for mining blocks, miners have employed a variety of techniques to maximize their profits.
- CPU Mining: This was the initial approach, simply running the mining algorithm on a computer's processor, ideally multi-threaded so that for a CPU with N-cores (or threads), N candidate blocks could be hashed at a time, improving the throughput.
- GPU Mining: Since GPUs are particularly well-suited to parallel-processing, the use of GPUs allowed for significantly increased hashing power and, for a time, heavily increased the demand for high-end graphics cards.