In contemporary usage, a picnic can be defined simply as a pleasure excursion at which a meal is eaten outdoors (al fresco or en plein air), ideally taking place in a beautiful landscape such as a park, beside a lake or with an interesting view and possibly at a public event such as before an open air theatre performance, and usually in summer. Descriptions of picnics show that the idea of a meal that was jointly contributed and was enjoyed out-of-doors were essential to a picnic from the early 19th century.

Picnics are often family-oriented but can also be an intimate occasion between two people, or a large get-together such as company picnics and church picnics. It is also sometimes combined with a cookout, usually a form of barbecue; either grilling (griddling, gridironing, or charbroiling), braising (by combining a charbroil or gridiron grill with a broth-filled pot), baking, or a combination of all of the above.

On romantic and family picnics a picnic basket and a blanket (to sit or recline on) are usually brought along. Outdoor games or some other form of entertainment are common at large picnics.

Some picnics are a potluck, an entertainment at which each person contributed some dish to a common table for all to share. When the picnic is not also a cookout, the food eaten is rarely hot, instead taking the form of deli sandwiches, finger food, fresh fruit, salad, cold meats and accompanied by chilled wine or champagne or soft drinks.