Here is a look at the Kurdistan Workers Party (PKK), as three Kurdish women, one of them a founding member of the militant group, were killed in Paris.
* PKK ORIGINS - Abdullah Ocalan founded the Marxist-Leninist group in 1978. It took up arms against Turkey in 1984 with the aim of creating an independent Kurdistan in the mainly Kurdish areas of Turkey, Iraq, Syria and Iran. It is now seeking greater Kurdish rights and limited autonomy in southeast Turkey.
* LOGISTICS - The PKK is listed as a terrorist organization by Ankara, the United States and the European Union and is estimated to have up to 8,000 people under arms, mostly based in the mountains of neighboring northern Iraq. It draws support from many Kurds in Turkey and among some Kurdish communities across Europe. Ankara has accused Syria of arming the rebels and allowing a PKK-linked party to control parts of the border region as a counter-weight to rebels fighting to overthrow President Bashar al-Assad.
* UPSURGE IN VIOLENCE - The last 18 months have seen the heaviest fighting between the PKK and Turkish forces in more than a decade. Since June 2011, when Turkish Prime Minister Tayyip Erdogan was re-elected to a third term, more than 800 people have been killed. This marks the deadliest outbreak of fighting since PKK leader Ocalan was captured in 1999, according to estimates by the International Crisis Group.
* OCALAN IN PRISON - Ocalan was captured and sentenced to death by a Turkish court in 1999, but the sentence was reduced to life imprisonment in October 2002 when Turkey abolished the death penalty. He is now imprisoned on Imrali island south of Istanbul and still commands the support of PKK members and sympathizers. Fighting dwindled for years after Ocalan's capture as a result of a string of unilateral PKK ceasefires. Some members of the PKK went on hunger strike in 2012 in part in protest at Ocalan's lack of access to lawyers for the last 15 months. The strike, which ended last November, helped convince the government to hold new talks with the PKK.
* POLITICAL PROGRESS - Turkey has now embarked on a new round of peace negotiations with Ocalan and media reports say they have agreed on the outline of a plan to end the nearly 30 year-old conflict which has killed 40,000 people. One part of a possible plan could involve releasing thousands of people accused of PKK links held in prison. Senior intelligence officials have previously held secret meetings with the PKK in Oslo. The Erdogan government has boosted Kurdish cultural and language rights since taking power a decade ago, but Kurdish politicians seek moves towards autonomy in the mainly Kurdish southeast.
Sources Reuters/Jane's World Insurgency and Terrorism Guide (Reporting by David Cutler, London Editorial Reference Unit)