This post was put together by Mark Holmes, thanks Mark.
Lent is a 40-day period of preparation for Easter observed by many Christians.
Easter Sunday commemorates Jesus Christ rising from the dead, and is the most important feast in the Christian year. Good Friday, immediately before it, commemorates Jesus' death on the cross, and the previous day (Maundy Thursday) commemorates Jesus' last meal, when the Eucharist or Holy Communion was instituted.
To prepare for these important feasts, Christians have traditionally observed Lent as a period of prayer, almsgiving (giving money to the poor), and fasting and self-denial. This is about remembering that some things matter more than material possessions, and recognising what they have done wrong and asking God for forgiveness. The idea is to be in fellowship with God by the time of Easter. Lent also commemorates the period of 40 days that, according to the Bible, Jesus spent in the desert earlier in his life, praying and fasting. (Don't worry too much about the 40 days: scholars think it was a Hebrew phrase meaning 'a long time'.)
Thanks to the Council of Nicaea in the year 325, Easter Sunday is the first Sunday after the first ecclesiastical full moon on or after the vernal equinox (21 March). So this year, it is 27 March. (That is, in the Western church: Eastern Orthodox churches have a different calendar.) So Lent starts next Wednesday, 9 February. (It comes to 40 days because they don't count Sundays - the Orthodox church doesn't count Saturdays either.)
Not very much of the Lenten observance of prayer, almsgiving and self-denial is obvious in British society today. But popular playground culture has adopted the self-denial in "giving something up for Lent" - like chocolate, or alcohol. In some churches, the ceremonial aspects are reduced a bit to focus on the basics - for example, statues are covered up with purple cloth, or there is less music.
Historically, fasting was taken much more seriously: you were only allowed one meal a day, and no meat, fish, eggs or milk. So during Lent, people had no use for milk and sugar. The tradition developed in Britain of using up these ingredients the day before Lent, by making pancakes. This day is called Shrove Tuesday, from the word "shrive", meaning to confess your sins, say sorry to God and do penance - as you do in Lent. The French name, Mardi Gras (Fat Tuesday), seems more honest. Some parts of the world don't just get all their milk and sugar out of the way before Lent, but all their partying, with a Carnival - which means "farewell to meat".