Définition et Signification de "old school"

What is the origin of the idiom "old school" and when to use it?

The idiom "old school" originated from the informal use of the term "school" as a reference to a particular approach, style, or set of values. The phrase gained prominence in the mid-20th century and has since evolved to denote a preference for traditional or conventional methods, often with a sense of nostalgia. This expression is used to imply a commitment to established practices, principles, or styles that were prevalent in the past, contrasting with more modern or innovative approaches.