In the US? Protected classes. This is the idea that some discrimination is so pervasive and damaging that it needs protection from the law, despite the fact that that directly conflicts with the idea that businesses should be able to be run as the owner likes. The harm of the latter is small compared to the harm of allowing the former, so the argument goes (and which I agree with, not that that matters to the answer).
If I decide my soup shop won't serve you because you ask a question or put your money on the counter instead of handing it to me, no problem, questions askers are not a protected class. You can trivially go to the restaurant next door and get served. If I decide I won't serve soup to anyone in a same sex relationship, someone of Jewish descent, women, or whatever, then there are legal protections in place that prohibit me from doing that.
I am not a lawyer, but this goes back before you were born. There was the civil Rights act of 1866 which banned discrimination due to race or color. The Civil Rights act of 1964 added sex, national origin, religion. In 1967 age discrimination was added, and in '73 disability. ADA was introduced in 1990, and that was expanded further in 2008. So now, for example, a business is required to make reasonable accommodations for a disability. But they don't have to hire you if you scream obscenities, or wear yellow shirts, or I dunno, are vocally planning to murder a politician or destroy a Government. None of those are protected classes. No requirement to do business with them or to hire them, or to keep them in your employ.
If I decide my soup shop won't serve you because you ask a question or put your money on the counter instead of handing it to me, no problem, questions askers are not a protected class. You can trivially go to the restaurant next door and get served. If I decide I won't serve soup to anyone in a same sex relationship, someone of Jewish descent, women, or whatever, then there are legal protections in place that prohibit me from doing that.
I am not a lawyer, but this goes back before you were born. There was the civil Rights act of 1866 which banned discrimination due to race or color. The Civil Rights act of 1964 added sex, national origin, religion. In 1967 age discrimination was added, and in '73 disability. ADA was introduced in 1990, and that was expanded further in 2008. So now, for example, a business is required to make reasonable accommodations for a disability. But they don't have to hire you if you scream obscenities, or wear yellow shirts, or I dunno, are vocally planning to murder a politician or destroy a Government. None of those are protected classes. No requirement to do business with them or to hire them, or to keep them in your employ.