A term applied to activities, ideas, products/services, etc., that are used/followed/supported by most people. MainstreamA term applied to activities, ideas, products/services, etc.... basically means ‘commonly used by people’. MainstreamA term applied to activities, ideas, products/services, etc.... as a marketingThe promotion and/or selling of a company, product, service,... term is the opposite to ‘niche’ or specialisedTo be highly skilled in a particular branch of a profession,.... Interestingly while ‘mainstream’ seems like a relatively modern word, it’s actually existed in this sense since about 1830.