It's Thursday, February 28, and it's Pope Benedict the XVI's last day as Pope. He announced his resignation earlier this month and his time as Pope officially ends this evening. The Pope is the head of the Roman Catholic church, Christianity is the world's largest religion and Catholics are the largest group of Christians. There are around 1.2 billion Catholics around the world. Yesterday, Pope Benedict made his final public speech in St.Peter's Square. That's part of Vatican city, the headquarters of the Catholic church and the world's smallest country. In yesterday's speech, the Pope talked about his spiritual journey during his nearly eight years as head of the church. There's been controversies and scandals surrounding the Catholic church, like accusations of some priests abusing children and claims of corruption. Some analysts think the Pope was referring to these issues during his speech.

"He spoke about how he had so much joy, he said in the church and in his eight years of reign, but he also talked about how that it'd been difficult times, he said it had been far from easy on occasion, he talked about how the church had come across agitated waters, and sometimes found itself of facing the different directions of the winds."

Pope Benedict is the first Pope in nearly 600 years to resign. What comes next? He'll still be called Benedict, the name he chose when he became Pope. He'll still be referred to as "His Holiness", but his official title will be Pope Emeritus. He'll live in Vatican city in a small monastery and Benedict is expected to devote his time to prayer and study. As for the Roman Catholic church, it has to elect a new Pope. And here is how that process happens.

"The Pope is the spiritual leader of 1.2 billion Catholics around the world and the most visible religious leader of any kind on the planet."

The new Pope is always chosen by the members of College of Cardinals. They are the highest office in the church under the Pope himself. Normally, when a papacy ends, either through death or resignation, cardinals from around the world gathered in the Rome, they had daily meetings to talk about the issues facing the church and the qualities the new Pope needs. We're talking about slightly over 100 cardinals who file into the Sistine Chapel cast ballots and pick a Pope.

Conclave is a term that comes from the two Latin words, meaning with a key, referes to the fact that the cardinals are locked behind closed doors while they go through a highly ceremonial process of casting ballots and then burning them, then it goes as long as it takes for someone to get two thirds, the shortest conclave in history took a couple of hours, the longeset one took three years.

In the old days, they would burn ballots, largely because they wanted to maintain the secrecy of the conclave, that is they didn't want the vote totals to get out. What they realized is that when people saw the smoke from chimney atop the Sistine Chapel, they knew a round of balloting had ended and so they came up with the system or they would put chemicals into the mix to turn the smoke black if no Pope had been elected, and white, if a Pope had been elected.

In theory according to the law of the church, any person who was eligible for ordination to the priesthood and therefore for an unmarried male, could be elected as Pope, but in practice, a new Pope will be elected from among cardinals who are voting, that is the cardinals who are under the age of 80 who will take part in this election. Which means that the roughly 150 cardinals aren't merely voters, they are all also candidates.

When a candidate cross that two thirds threshold, another cardinal will approach him and say, "Do you accept your canonically valid election as Supreme Pontiff? If he answers yes, from that moment forward, he becomes the Pope. The next question is by what name will you be known. And at that stage, the new Pope tells his brother cardinals what he wants to be called and then a few minutes later when the announcement was made from a balcony outside St.Peter's Square, the whole world will know the name of the new Pope.