Up your alley (also known as right down your alley) is an idiomatic expression used about topics or a field of interest that matches your skill set and takes a hold of your attention.
Saying that something is up in your alley indicates that that thing specifically matches your ability or talent.
Although, sometimes the expression just simply means you find something really attractive.
It is unclear who exactly coined the idiom, but certain records show that early versions of up in your alley were used as early as the 1930s U.S.
There are numerous derivatives to the expression. This can be explained with the etymology which indicates that the key element of the term is “alley”, which is often switched up with “street” or other topographical expressions.
This would conclude that the term always refers to a certain “home” in which one feels confident and stable.
Up your alley primarily spread in the British Isles, while other versions became more popular in the United States.
An example of the usage of the British English expression can be found in the 1945 novel Brideshead Revisited II, which contains a part that features the idiom: “…she is a jolly attractive girl, the sort of girl any chap would be glad to have—artistic, too, just down your alley.”