Blackmail is a crime in many jurisdictions whose legal systems derive from England. The precise definition varies, but a classic example would be if I knew you had committed a crime, and threatened to report it to the authorities unless you paid me. See for example 18 US Code 873 - <a href="https:&#x2F;&#x2F;www.law.cornell.edu&#x2F;uscode&#x2F;text&#x2F;18&#x2F;873" rel="nofollow">https:&#x2F;&#x2F;www.law.cornell.edu&#x2F;uscode&#x2F;text&#x2F;18&#x2F;873</a><p>No one would ever be found guilty of blackmail for simply saying &quot;Give me a pay rise or else I&#x27;ll resign&quot;. (But, &quot;Give me a pay rise or else I&#x27;ll report your illegal activities to the authorities&quot; would be blackmail.) The essence of blackmail is demanding money for an illegitimate reason - money which you are not legitimately due - and there is nothing inherently illegitimate about demanding a pay rise. It simply means that you put a different value on your own labour than your employer currently does, and if you and they cannot reach agreement on that value, you&#x27;ll look for someone else with whom you agree more.