In the 13th century the word hobby referred to a small horse or a pony. It later came to describe a toy horse — a hobbyhorse. It's from the hobbyhorse that the word's modern sense of “favorite pastime” evolved. A hobby is something that you do for fun — not money — and you typically do it fairly regularly.
hobby is this when a person is doing what they love. For example, how to collect stamps, stickers, collect various things. It's very interesting!
