Still life paintings traditionally depicted everyday natural or man-made objects and often contained religious or allegorical symbolism related to the items shown. According to Wikipedia, still lifes most commonly feature food, flowers, or household goods. Some modern still lifes break from tradition by using three-dimensional mixed media, found objects, photography, and video or sound to represent their subjects.

1. Traditional and Contemporary Meanings

3.  According to Wikipedia, still lifes depict mostly
commonplace subject matter, objects which may be
either natural (food, flowers, dead animals, plants,
rocks, or shells) or man-made (drinking glasses,
books, vases, jewelry, coins, pipes, and so on).

4.  With origins in the Middle Ages and Ancient Greco-
Roman art, Still-life paintings, particularly before 1700,
often contained religious and allegorical symbolism
relating to the objects depicted.

5.  Some modern still life breaks the two-dimensional
barrier and employs three-dimensional mixed media,
and uses found objects, photography, as well as video
and sound.