That’s interesting! In the US we have what’s called “employment-at-will.” Basically, that means as an employee, you are free to work or quit at your place of employment…you aren’t bound to the employer. You can quit any time for any reason...you can just walk away if you want. However, employers are also free to fire you, or terminate your employment, for any reason, too (NOTE: US employers can’t fire someone on the basis of sex, race, religion, or national origin…that’s against the law; for example, you can’t be fired for being a woman, but you can be fired if the employer simply doesn’t like the shirt you’re wearing (that would be a stretch, though)). Contracts are usually reserved for special circumstances. We also enter into contracts for special work that has a definite beginning and end (like a construction contract).