As an adjective, particular describes something specific, such as when you prefer one particular type of cereal over another. The noun form means specific points or details, as in the particulars of a police investigation.
The idea of particular referring to details comes from the Latin particula, which means "particle" or "small part," and in Middle English the word meant something that referred to a single person or thing. You can note that in the phrase "in particular" which means "especially." As in, one breed of dog in particular would suit you best, with your floppy ears and friendly personality.