what makes one share more difficult than another?

[Eli0t]

so when mining, what makes one share more difficult than another?

for some reason i thought it was the number of 0s but now im not so sure

[DannyHamilton]

It's not shares the are more difficult, it's blocks.

Blocks are made more difficult by reducing the target value for the hash.

Miners repeatedly calculate a SHA-256 hash of the block header (modifying a piece of data in the header each time so the resulting hash will have a different value) until the value of the resulting hash is less than a target value.  Increasing the number of leading zeros increases the difficulty by resulting in a lower target value.

As an analogy using base 10 numbers:

000543 is less than 473543, so when choosing a random number between 0 and 999999, it you are more likely (it is easier) to pick a number less than 473543 than to pick one less than 000543.

[Eli0t]

interesting thanks