Sara gave you some examples, here's more information "By" means near or next to. "By" also means through which. (preposition) 1. An example of by is a red house set adjacent to a green house.[ The red house was by the green house] 2. An example of by is the author of a novel.[ The play Othello is by Shakespeare] "By" means in the immediate region or to go past something. (adverb) 1. An example of by is how one describes the closeness of a church down the street.[ The church is close by the street] 2. An example of by is a bike rider passing a jogger on the street.[ The bike rider passed by the jogger along the street]

by - to pass a given point "I went by the store." The vending machine was by the entrance." - in reserve, not for immediate use "I put something by for her old age" or as in "byproduct" - a product made after something else happens