Jam

Jam is a term with several meanings across food, transportation, and music.

In culinary use, jam refers to a fruit preserve made by cooking crushed or chopped fruit with sugar until the mixture thickens. It is typically spread on bread or used as a dessert filling. Texture can range from smooth to chunky, depending on whether the fruit is mashed or left in pieces. Pectin and acidity help the mixture set, and sugar acts as a preservative. Jam differs from jelly, which is made from fruit juice, and from marmalade, which uses citrus fruit with peels. Commercial jams are produced by heating the mixture and sealing it in jars to extend shelf life.

A traffic jam is a condition in which vehicles become congested and movement slows or stops on road networks. Common causes include high traffic volume, accidents, roadworks, adverse weather, and bottlenecks at junctions. Effects include delays, increased fuel consumption, higher emissions, and driver frustration. Management approaches emphasize improving traffic flow, rapid incident response, infrastructure adjustments, public transit options, and incentives to shift demand away from peak periods.

In music, a jam or jam session is an informal gathering where musicians improvise together, often without a fixed arrangement. Jazz, blues, and rock players frequently participate. Sessions emphasize listening, responsiveness, and collective development, with players trading solos and developing ideas in real time. The concept extends to jam bands, groups known for long, improvised live performances.

Other uses include the verb to jam, meaning to press, pack, or obstruct something, such as a printer or mechanism. The term also applies to the culture surrounding informal, spontaneous musical collaboration and the broader idea of improvisational activity.