Real Dictionary

into
preposition: If you put one thing into another, you put the first thing inside the second.

into in American English
from the outside to the inside of; to the midst or depths of
adjective: pertaining to a function or map from one set to another set, the range of which is a proper subset of the second set, as the function f, from the set of all integers into the set of all perfect squares where f(x) = x2 for every integer
preposition: to the inside of; in toward

into in British English
preposition: to the interior or inner parts of