As geological processes apply pressure to dead biotic material over time, under suitable conditions it is transformed successively into:

• Peat, considered to be a precursor of coal, has industrial importance as a fuel in some regions, for example, Ireland and Finland. In its dehydrated form, peat is a highly effective absorbent for fuel and oil spills on land and water
• Lignite, also referred to as brown coal, is the lowest rank of coal and used almost exclusively as fuel for electric power generation. Jet is a compact form of lignite that is sometimes polished and has been used as an ornamental stone since the Upper Palaeolithic
• Sub-bituminous coal, whose properties range from those of lignite to those of bituminous coal are used primarily as fuel for steam-electric power generation. Additionally, it is an important source of light aromatic hydrocarbons for the chemical synthesis industry.
• Bituminous coal, dense sedimentary rock, black but sometimes dark brown, often with well-defined bands of bright and dull material, used primarily as fuel in steam-electric power generation, with substantial quantities also used for heat and power applications in manufacturing and to make coke
• Steam coal is a grade between bituminous coal and anthracite, once widely used as a fuel for steam locomotives. In this specialized use it is sometimes known as sea-coal in the U.S. Small steam coal (dry small steam nuts or DSSN) was used as a fuel for domestic water heating
• Anthracite, the highest rank; a harder, glossy, black coal used primarily for residential and commercial space heating. It may be divided further into metamorphically altered bituminous coal and petrified oil, as from the deposits in Pennsylvania
• Graphite, technically the highest rank, but difficult to ignite and is not so commonly used as fuel: it is mostly used in pencils and, when powdered, as a lubricant.

The classification of coal is generally based on the content of volatiles. However, the exact classification varies between countries. According to the German classification, coal is classified as follows:

The middle six grades in the table represent a progressive transition from the English-language sub-bituminous to bituminous coal, while the last class is an approximate equivalent to anthracite, but more inclusive (the U.S. anthracite has < 6% volatiles).

Cannel coal (sometimes called "candle coal"), is a variety of fine-grained, high-rank coal with significant hydrogen content. It consists primarily of "exinite" macerals, now termed "liptinite".

Countries with annual import higher than 30 million tonnes are shown.

Imports of Coal by Country and year (million short tons)

Country	2006	2007	2008	2009	Share
Japan	199.7	209.0	206.0	182.1	17.5%
China	42.0	56.2	44.5	151.9	14.5%
South Korea	84.1	94.1	107.1	109.9	10.6%
India	52.7	29.6	70.9	76.7	7.4%
Taiwan	69.1	72.5	70.9	64.6	6.2%
Germany	50.6	56.2	55.7	45.9	4.4%
United Kingdom	56.8	48.9	49.2	42.2	4.1%
Total	991.8	1,056.5	1,063.2	1,039.8	100%

Countries with annual export higher than 10 million tonnes are shown.

Exports of Coal by Country and year (million short tons)

Country	2007	2008	2009	Share
Australia	268.5	278.0	288.5	26.5%
Indonesia	221.9	228.2	261.4	24.0%
Russia	112.2	115.4	130.9	12.0%
Colombia	74.5	74.7	75.7	6.9%
South Africa	72.6	68.2	73.8	6.8%
USA	60.6	83.5	60.4	5.5%
China	75.4	68.8	38.4	3.5%
Canada	33.4	36.5	31.9	2.9%
Vietnam	35.1	21.3	28.2	2.6%
Kazakhstan	32.8	47.6	25.7	2.4%
Poland	20.1	16.1	14.6	1.3%
Total	1,073.4	1,087.3	1,090.8	100%

The reserve life is an estimate based only on current production levels and proved reserves level for the countries shown, and makes no assumptions of future production or even current production trends. This is a list of countries by coal production in 2009 based mostly on Statistical Review of World Energy 2010 published in 2010 by BP ranks countries with coal production larger than 100 millions tonnes.

Production of Coal by Country and year (million tonnes)

Country	2007	2008	2009	Share	Reserve Life (years)
China	2526.0	2782.0	3050.0	45.6 %	38
USA	1040.2	1062.8	973.2	15.8 %	245
India	478.4	521.7	557.6	6.2 %	105
EU	593.4	587.7	536.8	4.6 %	55
Australia	399.0	401.5	409.2	6.7 %	186
Russia	314.2	326.5	298.1	4.3 %	150+
Indonesia	217.4	229.5	252.5	3.6 %	17
South Africa	247.7	250.4	250.0	3.6 %	122
Germany	201.9	192.4	183.7	2.6 %	37
Poland	145.9	143.9	135.1	1.7 %	56
Kazakhstan	97.8	111.1	101.5	1.5 %	308
Total World	6,421.2	6,781.2	6,940.6	100 %	119

The 930 billion short tons of recoverable coal reserves estimated by the Energy Information Administration are equal to about 4,116 BBOE (billion barrels of oil equivalent). The amount of coal burned during 2007 was estimated at 7.075 billion short tons, or 133.179 quadrillion BTU's. This is an average of 18.8 million BTU per short ton. In terms of heat content, this is about 57,000,000 barrels (9,100,000 m³) of oil equivalent per day. By comparison in 2007, natural gas provided 51,000,000 barrels (8,100,000 m³) of oil equivalent per day, while oil provided 85,800,000 barrels per day.

BP, in its 2007 report, estimated at 2006 end that there were 909,064 million tons of proven coal reserves worldwide, or 147 years reserves-to-production ratio. This figure only includes reserves classified as "proven"; exploration drilling programs by mining companies, particularly in under-explored areas, are continually providing new reserves. In many cases, companies are aware of coal deposits that have not been sufficiently drilled to qualify as "proven". However, some nations haven't updated their information and assume reserves remain at the same levels even with withdrawals. Collective projections generally predict that global peak coal production may occur sometime around 2025 at 30 percent above current production in the best case scenario, depending on future coal production rates.

Of the three fossil fuels, coal has the most widely distributed reserves; coal is mined in over 100 countries, and on all continents except Antarctica. The largest reserves are found in the USA, Russia, China, India and Australia. Note the table below.

Proved recoverable coal reserves (million tons (teragrams))

Country	Bituminous & Anthracite	SubBituminous	Lignite	TOTAL	Percentage of World Total
United States	108,501	98,618	30,176	237,295	22.6
Russia	49,088	97,472	10,450	157,010	14.4
China	62,200	33,700	18,600	114,500	12.6
Australia	37,100	2,100	37,200	76,500	8.9
India	56,100	0	4,500	60,600	7.0
Germany	99	0	40,600	40,699	4.7
Ukraine	15,351	16,577	1,945	33,873	3.9
Kazakhstan	21,500	0	12,100	33,600	3.9
South Africa	30,156	0	0	30,156	3.5
Serbia	9	361	13,400	13,770	1.6
Colombia	6,366	380	0	6,746	0.8
Canada	3,474	872	2,236	6,528	0.8
Poland	4,338	0	1,371	5,709	0.7
Indonesia	1,520	2,904	1,105	5,529	0.6
Brazil	0	4,559	0	4,559	0.5
Greece	0	0	3,020	3,020	0.4
Bosnia and Herzegovina	484	0	2,369	2,853	0.3
Mongolia	1,170	0	1,350	2,520	0.3
Bulgaria	2	190	2,174	2,366	0.3
Pakistan	0	166	1,904	2,070	0.3
Turkey	529	0	1,814	2,343	0.3
Uzbekistan	47	0	1,853	1,900	0.2
Hungary	13	439	1,208	1,660	0.2
Thailand	0	0	1,239	1,239	0.1
Mexico	860	300	51	1,211	0.1
Iran	1,203	0	0	1,203	0.1
Czech Republic	192	0	908	1,100	0.1
Kyrgyzstan	0	0	812	812	0.1
Albania	0	0	794	794	0.1
North Korea	300	300	0	600	0.1
New Zealand	33	205	333-7,000	571-15,000	0.1
Spain	200	300	30	530	0.1
Laos	4	0	499	503	0.1
Zimbabwe	502	0	0	502	0.1
Argentina	0	0	500	500	0.1
All others	3,421	1,346	846	5,613	0.7
Total world	404,762	260,789	195,387	860,938	100