Maundy Thursday is also kown as Holy Thursday and Covenant Thursday. It commemorates the Last Supper of Jesus with the Apostles.The Mass of the Last Supper begins the Eastern Triduum. This is the three days of Friday, Saturday and Sunday of Holy Week commerorating the Passion, Death and Resurrection of Jesus.
The origin of the word "Maundy" is thought to come from the Latin "Mandatum", "Mandatum novum do vobis ut diligatus invicem sicut dilexi vos" which translated is Gospel of John 13:34, "A new commandment I give unto you, That ye love one another; as I have loved you." This was the statement Jesus made to explain his washing his disciples feet. That action is why Jesus has also been called the "servant king".
Jesus had previously said the whole of teachings could be summed up as Love God, and Love your neighbor as yourself. But here he goes even further and says love one another as I have loved you. In Christian terms this really comes down to saying that we need to love other humans as we are loved by God. God's love is shown to us in the life of Jesus and the self sacrifice of Jesus.
An alternative explanation for the term Maundy is that it derives from the medieval custom of the English royalty handing out "Maundy purses' of alms for the poor before the mass on that day.
Personally I prefer the former as truly Godly and the latter aslamely human. However the ambivalence and paradox of the word does clarify "unconditional love" and "conditional love", and explain perhaps why Jesus said that it would be as difficult for the rich to get into heaven as it would be for a camel to pass through the eye of a needle.
The washing of the feet is a traditional component of the Maundy Thursday service. In the Roman Catholic service the Mass of the Lord's Supper begins as usual , but the Gloria is accompanied by bells. The bells then are silent until the Easter Vigil. The procession taking the Blessed Sacrament to the place of reposition follows. After the altar is stripped bare. The 'stripping of the altar' is in preparation for sombre Good Friday.
In the Eastern Orthodox church the Passion Gospel (John 13:11 -18.1) is read followed by the troparion:
"Of Thy Mystical Supper, O Son of God, accept me today as a communicant; for I will not speak of The Mystery to thine enemies, neither will I give thee a kiss like Judas. But like the Thief will I confess Thee: Remember me, O Lord, in Thy Kingdom."
Around the world there are various local customs associated with Maundy Thursday. The Monarch of England gives "Maundy coins", in the Phillipines business establishments cease operations from Holy Thursday to Black Saturday. In some regions of Checkoslovakia children walk about in groups making noise with wooden rattles, with people coming out to give them money; the tradition of silent bells is observed in Luxemburg and instead children take to the streets to call people to come to church. In Sweden there's the tradition associated with old folklore that this is the day of the witches and the children dress up as witches, going about knocking on doors and getting candy.
One tradition that is observed in many places is the "tradition of visiting seven churches." This probably originated in Rome with visiting the "seven pilgrim churches."
Most of this material was derived from Wikipedia's Maundy Thursday while I must confess the commentary as my own.