Tar or liquid pitch[1]​ is a bituminous, viscous, dark and strong-smelling liquid substance obtained from the destructive distillation of certain materials, mainly coal, peat, bones and some resinous woods and other plant and mineral materials.

[2]​

[3]​ It has different industrial applications.

The word "tar" is used to describe several substances:

A good amount of this compound can be found in so-called "tar pits" (for example, Rancho La Brea, in Los Angeles). A variation is tar sand, a deposit containing various mixtures of sand (or rock) with bitumen or heavy crude oil instead of tar, as seen in the Tar Tunnels in Shropshire.

There is also "Rangoon tar", known as "Burmese oil" or "Burmese naphtha".

The sticky matter obtained from the combustion of tobacco is also called tar.[2] Tobacco tar is composed of thousands of chemicals, some of which are carcinogenic or classified as toxic waste. Among the substances that make up tar, there are polycyclic aromatic hydrocarbons, aromatic amines and inorganic compounds. It is important to note that tar clogs the lungs and affects breathing, being, like the other components of cigarettes, the cause of their toxicity.

Being a complex mixture of organic compounds, it is very difficult to speak of a specific composition or formula of tar, since it varies depending on the size of the carbon chain, temperature, the distillation process used and its origin.

Regarding coal tar, there are around 300 different components known, 50 of which can be separated and marketed, some of them are carcinogenic.[4]​.

Coal tar is formed below 600 °C and is mainly composed of paraffins, olefins, alcohols, phenols, and water; while at temperatures above 1000 °C, coke begins to form from the coal and the resulting tar will consist mainly of aromatic hydrocarbons, phenols, and some nitrogen, sulfur and oxygen compounds.

These variations indicate that most of the tar compounds do not exist in the coal from the beginning, but are formed during the coking process.