The phrase "a chip off the old block" is an idiomatic expression that means someone is very similar to their parent or guardian in terms of personality, behavior, or characteristics. It suggests that the child has inherited certain traits from their parents and these traits are evident in their actions or behaviors. The phrase originated in the 19th century when woodworkers would chip off a small piece of wood from an old block to make it easier for them to work with, thus passing on its characteristics to the new piece. Today, the phrase is used more broadly to describe any resemblance between two people who are related or close in age and experience.