Ethereum Cookbook

revert()

1. revert() works just like the require() function, but use it for more complex conditions:

if (msg.sender != owner) {     revert(); }

2. revert also uses the 0xfd opcode to raise exceptions, so it supports the return message and gas refund functionalities:

if (!condition) {    revert("Error Message");}

3. If you have complex nested if-else control flow statements, use the revert() method instead of the require() method.
4. Both require and revert functions should be used more often. They are generally used at the beginning of a function.