In British English, the verb to quit is mostly used informally. In contexts such as controlling an addiction, where American English uses to quit even in quite formal circumstances, formal British English prefers to give up - "I gave up smoking a year ago"; "You should give up late nights if you want to improve your studies."
When we want to stop working at the end of the day, we also ignore
quit. We usually stop. If it is at the end of our career, we have given up (or left) our job, handed in our notice (less formally, our cards) or, least formally, packed it in. We can also say, where the Americans at least in films announce dramatically 'I quit', I resign.
The past form is usually quit, for both the past tense and the past participle. In more traditional British English, it was often quitted (as in the epitaph (1804) in Wells Cathedral for one who had "quitted the profession of the law"); but this is not much heard these days - and never, AWE believes, in American English.
- See also quit (irregular verb).