A decade ago, when American bomber jets and special forces forced the Taliban regime from power in Afghanistan, the movement which was born in the religious schools of Pakistan's tribal belts seemed shattered, never to return.
Since then, the various groups and factions of the Taliban - which means "students" in Arabic and Pashto - have split, regrouped and coalesced into an effective if diffuse guerrilla movement operating in Afghanistan and Pakistan.
Here are some questions and answers about who the Taliban factions are, and how the fight against them is going:
Who are the Taliban?
The Taliban include several loosely allied factions in both Pakistan and Afghanistan. The biggest are the Afghan Taliban, the Haqqani network and the Pakistani Taliban. Mullah Omar is still the nominal head of the entire Taliban movement and most other factions in both Pakistan and Afghanistan swear loyalty to him.
Given the dispersed nature of the groups, the Taliban factions often act like franchises, comprised of myriad regional cells that operate independently at the local level, but which follow the grand strategy and Islamic principles of the movement's shadowy leadership - primarily Omar's.
Where are they based?
Militant cells are scattered all across both countries but in Afghanistan are particularly strong in the south, southwest and the eastern frontier with Pakistan. In Pakistan, they operate in the borderlands known as the Federally Administered Tribal Areas, and in the northwest of the country bordering Afghanistan.
Support from people
In many parts of Afghanistan, and particularly among ethnic Tajiks and Hazaras in the north and northeast, many of whom suffered under their rule, the Afghan Taliban are reviled. To some Pashtuns, however, they are seen as defenders of Islam, battling foreign invaders. This view of the Afghan Taliban is also widely held in Pakistan.
State of the fight against the Taliban?
Nato-led and Afghan forces have reported success in securing parts of the country but there is no guarantee they can keep the Taliban at bay, especially beyond the planned withdrawal of foreign combat troops by the end of 2014.
In Pakistan, political leaders said after an all-party meeting attended by top military and intelligence officials last month they would seek reconciliation with militants to end the insurgency.