Who are Somalia's al-Shabab?
Islamist militant group al-Shabab is battling the UN-backed government in Somalia, and is suspected of links to a string of attacks in neighbouring Kenya. The group, which is linked to al-Qaeda, has been pushed out of most of the main towns it once controlled, but it remains a potent threat.Who are al-Shabab?
Al-Shabab means The Youth in Arabic.
It emerged as the radical youth wing of Somalia's now-defunct Union of Islamic Courts, which controlled Mogadishu in 2006, before being forced out by Ethiopian forces.
There are numerous reports of foreign jihadists going to Somalia to help al-Shabab, and the group has claimed to be allied with al-Qaeda.
It is banned as a terrorist group by both the US and the UK and is believed to have between 7,000 and 9,000 fighters.What is al-Shabab doing in Kenya?
Somali al-Qaeda fighters are accused links to terror attacks in Kenya in both 1998 - on the US embassy - and 2002 - on Israeli targets around Mombasa.
In 2011, al-Shabab carried out a series of attacks and kidnappings across the border in Kenya.
Kenya responded by sending troops into Somali territory to battle the militants.
Since then sporadic attacks have continued across Kenya. The biggest attack was on Nairobi's Westgate shopping centre in 2013 when at least 68 people died.
Analysts say the militants often enter and leave Kenya without being intercepted. Their fighters are said to get medical treatment in Nairobi.
Earlier this year, there were riots in Mombasa after a radical Muslim cleric who was accused of recruiting youngsters for al-Shabab was shot dead.How much of Somalia does al-Shabab control?
Although it has lost control of most towns and cities, it still dominates in many rural areas.
It was forced out of the capital, Mogadishu, in August 2011 and left the vital port of Kismayo in September 2012.
The loss of Kismayo has hit al-Shabab's finances, as it used to earn money by taking a cut of the town's lucrative charcoal trade.
Although African Union (AU) forces are trying to squeeze al-Shabab further, the group is still able to carry out suicide attacks in Mogadishu and elsewhere.
Al-Shabab advocates the Saudi-inspired Wahhabi version of Islam, while most Somalis are Sufis.
It has imposed a strict version of Sharia in areas under its control, including stoning to death women accused of adultery and amputating the hands of thieves.Who is al-Shabab's leader?
Ahmed Abdi Godane is the head of the group. Known as Mukhtar Abu Zubair, he comes from the northern breakaway region of Somaliland.
He is rarely seen in public. His predecessor, Moalim Aden Hashi Ayro, was killed in a US air strike in 2008.
Godane, who was behind the group's tie-up with al-Qaeda and has a hard-line, international agenda has emerged victorious from an internal power-struggle.
His rival, Sheikh Hassan Dahir Aweys, is more focused on the struggle within Somalia. He is now in government custody, while several of his allies have been killed.What are al-Shabab's foreign links?
In a joint video released in February 2012, Godane said he "pledged obedience" to al-Qaeda head Ayman al-Zawahiri.
The two groups have long worked together and foreigners are known to fight alongside Somali militants.
US officials worry that as al-Qaeda retreats in Afghanistan and Pakistan following the killing of Osama Bin Laden, fighters will increasingly take refuge in Somalia.
There have also been numerous reports that al-Shabab may have formed some links with other militants groups in Africa, such as Boko Haram in Nigeria and al-Qaeda in the Islamic Maghreb, based in the Sahara desert.What is happening in Somalia?
Somalia has not had an effective national government for more than 20 years, during which much of the country has been a war-zone.
Al-Shabab gained support by promising people security. But its credibility was knocked when it rejected Western food aid to combat a 2011 drought and famine.
With Mogadishu and other towns now under government control, there is a new feeling of optimism and many Somalis have returned from exile, bringing their money and skills with them.
Basic services such as street-lighting, dry cleaning and rubbish collection resuming in the capital.