The Vatican has announced Pope Francis has died at the age of 88.

It comes just a day after he made a public appearance in Vatican City, and so weeks after the leader of the Catholic Church battled ill-health.

The pope's death will prompt a period of mourning, after which all cardinals under the age of 80 will convene to pick the next leader of the Catholic Church.

Here's some questions answered about the conclave and the process of picking a new pope.

What is a papal conclave?

It comes from the Latin, cum clave, meaning, with a key.

It is the assembly of cardinals to elect a new pope and the system of strict seclusion to which they submit.

Only cardinals under the age of 80 are allowed to vote, although they can take part in the conclave.

There are currently 252 cardinals, 138 of whom are cardinal electors.

The most recent papal conclave occurred in 2013, when Jorge Mario Bergoglio from Argentina was elected as Pope Francis, succeeding the retiring Pope Benedict XVI.

What happens when a pope dies?

Once the death is verified by the cardinal camerlengo Cardinal Kevin Farrell, the representative of the Sacred College of Cardinals, he arranges for the pope's ring, known as Fisherman's Ring and the papal seal to be broken.

This symbolises the end of Pope Francis' authority.

Mourning rites last nine days, with the date of the funeral and burial to be decided by the cardinals.

Length of time between the death of the Pope to the beginning of the conclave?

Usually 15 to 20 days.

Once in Rome the cardinals live, eat and meet together under strict security measures.

They reside in a hotel-like building constructed for visiting clergy at the Vatican.

The area of the papal conclave is completely sealed off for the duration of the gathering.

Only cardinals and a few other people with specific roles are allowed to enter.

The cardinals are banned from using any phones or personal computers.

How is a decision made on electing a new pope?

The cardinals meet in the Sistine Chapel and vote by secret ballot until a candidate is selected.

A two-thirds majority vote is required to elect the new pontiff.

One ballot is held on the first day of the conclave and four on each subsequent day. Two in the morning and two in the afternoon.

Immediately after the count, the ballots and all related notes are burned in a stove in the chapel.

The colour of the smoke from a chimney enables the crowd in St Peter's Square to know if a result has been confirmed or not. When no one has received the required majority the smoke is black.

A successful candidate gets white smoke. Chemicals are used to determine the colour.

The bells of St Peter's Basilica will also peal when a new pope is elected. Pope Francis was elected on the fifth ballot.

What happens next?

The man elected by his fellow cardinals is then asked does he accept the position. If he does, then a senior cardinal will appear on the balcony overlooking the square and says to the crowd, "Habemus papam", we have a pope.

Soon after that the new pope appears and blesses the crowd.

An inauguration ceremony usually takes place a few days later.