Question: How many active volcanoes does Indonesia have?
About the article "Indonesia", section "Geography".

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There is no single standard definition for a volcano.
It can be defined from individual vents, volcanic edificies or volcanic fields.
Interior of ancient volcanoes may have been eroded, creating a new subsurface magma chamber as a separate volcano.
Many contemporary active volcanoes rise as young parasitic cones from flank vents or at a central crater.
Some volcanic cones are grouped into one volcano name, for instance, the Tengger caldera complex, although individual vents are named by local people.
The status of a volcano, either active or dormant, cannot be defined precisely.
An indication of a volcano is determined by either its historical records, radiocarbon dating, or geothermal activities.
The primary source of the list below is taken from the "Volcanoes of the World" book, compiled by two volcanologists Tom Simkin and Lee Siebert, in which active volcanoes in the past 10,000 years (Holocene) are listed.
Particularly for Indonesia, Simkin and Siebert used a catalogue of active volcanoes from the International Association of Volcanology and Chemistry of the Earth's Interior publication series.
The Simkin and Siebert list is the most complete list of volcanoes in Indonesia, but the accuracy of the record varies from one region to another in terms of contemporary activities and fatalities in recent eruptions.
Complementary sources for the latest volcanic data are taken from the Volcanological Survey of Indonesia, a governmental institution which is responsible for volcanic activities and geological hazard mitigation in Indonesia, and some academic resources. 
VDAP hold workshops and training courses around the world.
Many of these involve remote sensing and Geographic information system (GIS) modelling.
VDAP present a six week international study of active volcanoes course in Hawaii training geologists and civil workers in how to monitor volcanoes. 
<onlyinclude>The geography of Indonesia is dominated by volcanoes that are formed due to subduction zones between the Eurasian plate and the Indo-Australian plate.</onlyinclude> Some of the volcanoes are notable for their eruptions, for instance, Krakatau for its global effects in 1883, Lake Toba for its supervolcanic eruption estimated to have occurred 74,000 years before present which was responsible for six years of volcanic winter, and Mount Tambora for the most violent eruption in recorded history in 1815.
Volcanoes in Indonesia are part of the Pacific Ring of Fire.
The 150 entries in the list below are grouped into six geographical regions, four of which belong to the volcanoes of the Sunda Arc trench system.
The remaining two groups are volcanoes of Halmahera, including its surrounding volcanic islands, and volcanoes of Sulawesi and the Sangihe Islands.
The latter group is in one volcanic arc together with the Philippine volcanoes.
The most active volcanoes are Kelut and Merapi on Java island which have been responsible for thousands of deaths in the region.
Since AD 1000, Kelut has erupted more than 30 times, of which the largest eruption was at scale 5 on the Volcanic Explosivity Index (VEI), while Mount Merapi has erupted more than 80 times.
The International Association of Volcanology and Chemistry of the Earth's Interior has named Mount Merapi as a Decade Volcano since 1995 because of its high volcanic activity.
In 2012, Indonesia has 127 active volcanoes with about 5 million people have activities within the danger zone.
The earthquake and tsunami event of December 26, 2004 is thought to bring disruption to the volcanoes' eruption pattern.
The 2010 eruption of Mount Sinabung, which has no recorded eruption since the 1600s, is presented as one possible example of the hypothesis.
The word for "Mount" in Indonesian and many regional languages of the country (such as Javanese) is "Gunung".
Thus, Mount Merapi for example, is referred to as "Gunung Merapi" in Indonesian and also in some English-based sites. 
  List of volcanoes in Indonesia  
There is no consensus among volcanologists on how to define an "active" volcano.
The lifespan of a volcano can vary from months to several million years, making such a distinction sometimes meaningless when compared to the lifespans of humans or even civilizations.
For example, many of Earth's volcanoes have erupted dozens of times in the past few thousand years but are not currently showing signs of eruption.
Given the long lifespan of such volcanoes, they are very active.
By human lifespans, however, they are not.
Scientists usually consider a volcano to be "erupting" or "likely to erupt" if it is currently erupting, or showing signs of unrest such as unusual earthquake activity or significant new gas emissions.
Most scientists consider a volcano "active" if it has erupted in the last 10,000 years (Holocene times) – the Smithsonian Global Volcanism Program uses this definition of "active".
There are about 1500 active volcanoes in the world – the majority along the Pacific Ring of Fire – and around 50 of these erupt each year.
An estimated 500 million people live near active volcanoes.
"Historical time" (or recorded history) is another timeframe for "active".
The "Catalogue of the Active Volcanoes of the World", published by the International Association of Volcanology, uses this definition, by which there are more than 500 active volcanoes.
However, the span of recorded history differs from region to region.
In China and the Mediterranean, it reaches back nearly 3,000 years, but in the Pacific Northwest of the United States and Canada, it reaches back less than 300 years, and in Hawaii and New Zealand, only around 200 years.
As of 2013, the following are considered Earth's most active volcanoes:  Kīlauea, the famous Hawaiin volcano, has been in continuous, effusive eruption for thirty years, and has the longest-observed lava lake.
Mount Etna and nearby Stromboli, two Mediterranean volcanoes in "almost continuous eruption" since antiquity.
Mount Yasur, in Vanuatu, has been erupting "nearly continuously" for over 800 years.
The longest currently ongoing (but not necessarily continuous) volcanic eruptive phases are:  Mount Yasur, 111 years  Mount Etna, 109 years  Stromboli, 108 years  Santa María, 101 years  Sangay, 94 years Other very active volcanoes include:  Mount Nyiragongo and its neighbor, Nyamuragira, are Africa's most active volcanoes.
Piton de la Fournaise, in Réunion, erupts frequently enough to be a tourist attraction.
Erta Ale, in the Afar Triangle, has maintained a lava lake since at least 1906.
Mount Erebus, in Antarctica, has maintained a lava lake since at least 1972.
Mount Merapi  Ol Doinyo Lengai  Ambrym  Arenal Volcano  Pacaya  Klyuchevskaya Sopka  Sheveluch