3 - Voting rituals
Voting is held in the Sistine Chapel, "where everything is conducive to an awareness of the presence of God, in whose sight each person will one day be judged".
On the day the conclave begins, the cardinals celebrate Mass in the morning before walking in procession to the chapel.
Once the cardinals are inside the conclave area, they have to swear an oath of secrecy. Then, the Latin command "extra omnes" ("everyone out") instructs all those not involved in the election to leave before the doors are closed.
The cardinals have the option of holding a single ballot on the afternoon of the first day. From the second day, two ballots are held in the morning and two in the afternoon.
The ballot paper is rectangular. Printed on the upper half are the words "Eligio in Summum Pontificem" ("I elect as Supreme Pontiff"). Below is a space for the name of the person chosen. The cardinals are instructed to write the name in a way that does not identify them, and to fold the paper twice.
Then, in order of precedence, each cardinal holds up the ballot so it can be seen, and carries it to the altar, where a chalice is covered by a silver plate.
The cardinal says aloud: "I call as my witness Christ the Lord who will be my judge, that my vote is given to the one who before God I think should be elected."
He places his ballot paper on the plate, and then drops it into the chalice. After all the votes have been cast, the papers are mixed, counted and opened.
As the papers are counted, one of the scrutineers calls out the names of those cardinals who have received votes. He pierces each paper with a needle - through the word "Eligio" - placing all the ballots on a single thread.
After the numbers have been checked, all the ballot papers are burned – giving off the smoke visible to onlookers outside which traditionally turns from black to white once a new pope has been chosen.
Damp straw was once added to the stove to turn the smoke black, but over the years there has often been confusion over the colour of the smoke.
At the two conclaves in 1978, chemicals were added - but there were still complaints about "grey" smoke.
If a second vote is to take place immediately, the ballots from the first vote are put on one side and then burned together with those from the second vote. The process continues until one candidate has achieved the required majority.