Peshmergas - the word means "ready to die" - has become the accepted term for the Kurdish fighters in northern Iraq.
Peshmergas have few heavy guns - this is a captured Iraqi weapon
But who are they?
Most are loyal to either the Kurdistan Democratic Party (KDP) or the Patriotic Union of Kurdistan (PUK).
The KDP, led by Massoud Barzani, and the PUK, led by Jalal Talabani, each have about 25,000 to 30,000 fighters.
Many are veterans of years of fighting against Iraq and against each other - the current alliance is a very recent development.
The vast majority are men, though there is a 500-strong PUK women's battalion, run by 27-year-old Lieutenant Sirwa Ismael, which was formed in 1996.
The PUK peshmergas include a women's battalion
Both the KDP and PUK have set up military academies over the past decade, teaching such things as maths, computer science and history as well as weapons use, tactical awareness and strategy.
But their armaments remain at militia levels.
Kalashnikov-type assault rifles are commonplace, as are rocket-propelled grenade launchers - said to be obtainable for $25 in the arms bazaar in Irbil, the administrative heart of the pre-war Kurdish-run enclave in northern Iraq.
They also have a limited amount of towed artillery, some of it captured from Iraqi forces which fled from Irbil during the Kurdish uprising in 1991, or in the latest fighting.
But there are no armoured vehicles or tanks. Ordinary pick-up trucks and other civilian vehicles are the most common means of transport.
There are also other fighters who have made common cause, such as the IMK, with an armed militia of several hundred - one of the groups representing the ethnic Turkomans centred on Mosul and Kirkuk.
After the collapse of the Kurdish uprising in 1991, both the KDP and the PUK opened negotiations with the Iraqi Government.
KDP fighters, with their yellow flag, are working with US special forces
In elections in 1992, power was split almost 50/50 between the two parties but rivalry soon turned to civil war.
In 1996, the KDP got the backing of Saddam Hussein against the PUK, but the latter fought back.
Both sides then claimed jurisdiction over the whole of Iraqi Kurdistan, though the KDP is concentrated in the north, the PUK in the south.
In 1998, the KDP and PUK leaders signed a peace agreement in Washington.
But it was not until 2002 - with the looming prospect of a US-led war on Iraq - that there were joint discussions with other Iraqi groups, aimed at co-ordinating opposition.
There is now a joint command centre.
American and British intelligence officials are known to have been liaising with the peshmergas for some time and, for political reasons, the fighters are under the nominal control of US special forces in northern Iraq.
Some of the KDP's most senior military commanders were injured when a US warplane mistakenly attacked a convoy they were in last week.
Wajy Barzani, Massoud Barzani's younger brother and head of the KDP special forces, received critical head wounds.