Egypt has witnessed the overthrow of two presidents since the start of the Arab Spring.
Eighteen days of mass protests forced Hosni Mubarak to resign in February 2011, after three decades in power. He was convicted of complicity in the deaths of 846 people killed during the uprising, but the verdict was overturned on appeal.
Following Mr Mubarak's resignation, the Supreme Council of the Armed Forces (Scaf) assumed presidential powers. Parliamentary elections in 2011-12 saw overwhelming victories for the Islamist Muslim Brotherhood's Freedom and Justice Party and Salafist al-Nour party.
In June 2012, the Brotherhood's Mohammed Morsi was elected president. He swiftly revoked a controversial Scaf decree that limited his powers, dissolved the House of Representatives and changed the military's leadership, naming Gen Abdul Fattah al-Sisi as chief of staff and defence minister.
Public opposition to Mr Morsi began to build in November 2012, when he issued a decree granting himself far-reaching powers, and were fuelled by the passage of what many considered an Islamist-leaning draft constitution.
Mr Morsi was deposed by the military in June 2013 after millions of protesters took to the streets and replaced by an interim government.
Security forces then launched a crackdown on the Muslim Brotherhood, killing almost 1,000 people at two pro-Morsi sit-ins in Cairo.
In December 2013, a constituent assembly finished drafting a new constitution to replace the 2012 charter.
Where are we now?
Egypt is polarised between supporters of the interim government and the military on the one-hand, and supporters of the Muslim Brotherhood and those who fear the authorities have become too repressive on the other.
Some analysts say Egypt has returned to the kind of police state which the revolution aimed to remove.
A referendum will be held on the redrafted constitution, followed by parliamentary and presidential elections in 2014. It is unclear whether the hugely popular armed forces chief Gen Sisi will stand.