What is the plum pudding model?

Could you please elaborate on the concept of the plum pudding model? I'm intrigued to know how this model came to be and what it represents in the realm of atomic structure. Is it a metaphorical portrayal or a more literal depiction? Additionally, what are its key characteristics and how does it differ from other prevailing theories of atomic composition during its time? I'm particularly interested in how it shaped our understanding of matter and how it eventually evolved with the advent of new scientific discoveries.