A hash algorithm is a cryptographic algorithm that can only be encrypted but not decrypted. It can convert information of any length into a string of fixed length.
This string has three characteristics:
Even if the input value changes only a little, the output hash value will be very different.
Only the exact same input value can get the exact same output value.
There is no law between the input value and the output value, so the input value cannot be calculated from the output value. To find the specified output value, you can only use the enumeration method to continuously replace the input value and find the output value that meets the conditions.
The hash algorithm ensures that Bitcoin mining cannot reverse the results. Therefore, the miners continue to perform calculations, essentially brute-forcing the correct input value, and whoever finds it first will be rewarded in Bitcoin.