In the US it technically varies state to state though most states are now "at will", you can leave at any time (you can just walk out one day and never return a

In the US it technically varies state to state though most states are now "at will", you can leave at any time (you can just walk out one day and never return and that's legal though rude) and the two weeks is just a common courtesy. The flip side of this is the company can fire or lay you off at anytime. So while 2 weeks notice may not seem like a lot, the system we have here is actually potentially much harsher for employees than employers. As with the 2 week notice courtesy from employees to employers, most places will offer some sort of severance pay to soften the blow, entice employees to sign an NDA and smooth over any legal challenges that might pop up despite the "at will" employment situation.