crack(s) in basement wall

[mostsmooth]

another homeowner question
so im in the basement and notice a crack in the basement wall. im not quite sure what type of block the wall is made of, but theres a hairline-ish crack running from the top of the wall, almost down to the basement floor. the crack doesnt stay between the blocks (meaning it does stay in the cement between the blocks going down,right,down,right etc.), it goes across them as well. are these types of things normal?
this may or may not be a very stupid question, i dont know.
thanks in advance