Sour crude is high in sulfur. Sweet crude is low in sulfur.

Petroleum is considered "sweet" if it contains less than 0.5% sulphur. Sour crude oil has >0.5% sulphur. Sweet crude oil also contains small amounts of hydrogen sulfide (H2S) and carbon dioxide (CO2).

This terminology depends on the sulfur content of the crude oil. Sweet crude oil contains less than 5% of sulfur, while sour contains over 5%/. In the nineteenth century, the oil would be tasted to determine its composition, and the lower sulfur content is reported to give it a slightly sweet taste and pleasant smell.

Crude oil is mixture of many compounds. Most of the compounds are composed of hydrogen and carbon, so they are called hydrocarbons. Oxygen, nitrogen, sulfur and various trace metals also can be found in crude oil.

When there is significant concentrations of sulfur, the crude is considered sour crude.

See links.

There are 3 different types of Crude Oil,

1) Light sweet (WTI= West Texas Intermediate): High-quality, Sweet oil, traded at the NYMEX (Newyork Exchange)

2) North Sea Brent (Sourced from the North Sea): Light oil

3) Oman Dubai: Sour oil

(Crude oil is light if if the density is low & heavy if the density is high. Sweet if sulfur content is low and Sour if sulfur is high).

Now check the day today price at market....

Crude oil is a very complex mixture of hydrocarbon compounds with some inorganic compounds. Simple quality terms (light/ heavy and sour/ sweet) are defined for convenience and are inadequate terms to fully characterize the crude.

However, as discussed in the links, a crude that has less than 0.5% sulfur content is sweet crude. Oil that is between 37 to 42 degrees API in density is light oil. Other definitions exist (see link), however this appears the range used for US produced crude.

Light sweet crude will sell for higher prices than other grades, (Heavy sour, heavy sweet, light sour). Many countries produce light sweet crude including Russia, Saudi Arabia, Iraq, Brazil, Angola, Nigeria, and the US.

Please see related links.