The hardline Islamic Taliban movement has proved to be a formidable fighting force in Afghanistan and a major threat to its government.
The group that was removed from power by a US-led invasion in 2001 has gradually regained its strength and now controls and influences more territory than at any point since that time.
Led by Mawlawi Hibatullah Akhundzada, a hardline religious scholar, the Taliban have been in direct talks with the US since 2018, with both sides looking to end the long-running conflict that has cost tens of thousands of lives.
The Taliban, or "students" in the Pashto language, emerged in the early 1990s in northern Pakistan following the withdrawal of Soviet troops from Afghanistan.
It is believed that the predominantly Pashtun movement first appeared in religious seminaries - mostly paid for by money from Saudi Arabia - which preached a hardline form of Sunni Islam.
The promise made by the Taliban - in Pashtun areas straddling Pakistan and Afghanistan - was to restore peace and security and enforce their own austere version of Sharia, or Islamic law, once in power.
From south-western Afghanistan, the Taliban quickly extended their influence.
In September 1995 they captured the province of Herat, bordering Iran.
Exactly one year later, they captured the Afghan capital, Kabul, overthrowing the regime of President Burhanuddin Rabbani - one of the founding fathers of the Afghan mujahideen.
By 1998, the Taliban were in control of almost 90% of Afghanistan.
Afghans, weary of the mujahideen's excesses and infighting after the Soviets were driven out, generally welcomed the Taliban when they first appeared on the scene.
Their early popularity was largely due to their success in stamping out corruption, curbing lawlessness and making the roads and the areas under their control safe for commerce to flourish.
But the Taliban also introduced or supported Islamic punishments - such as public executions of convicted murderers and adulterers, and amputations for those found guilty of theft.
Men were required to grow beards and women had to wear the all-covering burka.
The Taliban banned television, music and cinema, and disapproved of girls aged 10 and over going to school.
They were accused of various human rights and cultural abuses. One notorious example was in 2001, when the Taliban went ahead with the destruction of the famous Bamiyan Buddha statues in central Afghanistan, despite international outrage.
Pakistan has repeatedly denied that it was the architect of the Taliban enterprise.
But there is little doubt that many Afghans who initially joined the movement were educated in madrassas (religious schools) in Pakistan.
Pakistan was also one of only three countries, along with Saudi Arabia and the United Arab Emirates (UAE), which recognised the Taliban when they were in power in Afghanistan.
It was also the last country to break diplomatic ties with the Taliban.
At one point the Taliban threatened to destabilise Pakistan from areas they controlled in the north-west. What was arguably one of the most internationally criticised of all Pakistani Taliban attacks took place in October 2012, when schoolgirl Malala Yousafzai was attacked on her way home in the town of Mingora.
However, a major military offensive greatly reduced the group's influence. At least three key figures of the Pakistani Taliban were killed in US drone strikes in 2013, including the group's leader Hakimullah Mehsud.
The attention of the world was drawn to the Taliban in Afghanistan following the attacks on the World Trade Center in September 2001.
The Taliban were accused of providing a sanctuary to Osama Bin Laden and the al-Qaeda movement who were blamed for the attacks.
On October 7, 2001, a US-led military coalition invaded Afghanistan and by the first week of December the Taliban regime had collapsed.
The group's then-leader, Mullah Mohammad Omar, and other senior figures evaded capture despite one of the largest manhunts in the world.
Many senior Taliban leaders reportedly took refuge in the Pakistani city of Quetta, from where they guided the Taliban.
But the existence of what was dubbed the "Quetta Shura" was denied by Islamabad.
Despite ever higher numbers of foreign troops, the Taliban gradually regained and then extended their influence, rendering vast tracts of Afghanistan insecure, and violence in the country returned to levels not seen since 2001.
There were numerous Taliban attacks on Kabul and, in September 2012, the group carried out a high-profile raid on Nato's Camp Bastion base.
Hopes of a negotiated peace were raised in 2013 when the Taliban announced plans to open an office in Qatar. However, mistrust on all sides remained high and violence continued.
In August 2015 the Taliban admitted they had covered up Mullah Omar's death for more than two years.
The following month the group said it had put aside weeks of infighting and rallied around a new leader in the form of Mullah Mansour, who had been the deputy of Mullah Omar.
At around the same time the Taliban seized control of a provincial capital for the first time since their defeat in 2001, taking control of the strategically important city of Kunduz.
Mullah Mansour was killed in a US drone strike in May 2016 and replaced by his deputy Mawlawi Hibatullah Akhundzada.