The Catholic Encyclopedia defines almsgiving as "any material favour done to assist the needy, and prompted by charity."
The following is a collection of excerpts from the beautiful message (written for last year's Lent) from Pope Benedict XVI on the purpose of almsgiving during Lent. I'm not nearly as eloquent as he, so I'll let him do most of the talking for this post. :-)
"For this year’s Lenten Message, I wish to spend some time reflecting on the practice of almsgiving, which represents a specific way to assist those in need and, at the same time, an exercise in self-denial to free us from attachment to worldly goods."
"According to the teaching of the Gospel, we are not owners but rather administrators of the goods we possess: these, then, are not to be considered as our exclusive possession, but means through which the Lord calls each one of us to act as a steward of His providence for our neighbor."
"[Jesus] made Himself poor to enrich us out of His poverty (cf. 2 Cor 8,9); He gave His entire self for us. Lent, also through the practice of almsgiving, inspires us to follow His example. In His school, we can learn to make of our lives a total gift; imitating Him, we are able to make ourselves available, not so much in giving a part of what we possess, but our very selves. Cannot the entire Gospel be summarized perhaps in the one commandment of love? The Lenten practice of almsgiving thus becomes a means to deepen our Christian vocation. In gratuitously offering himself, the Christian bears witness that it is love and not material richness that determines the laws of his existence. Love, then, gives almsgiving its value; it inspires various forms of giving, according to the possibilities and conditions of each person."
"Dear brothers and sisters, Lent invites us to “train ourselves” spiritually, also through the practice of almsgiving, in order to grow in charity and recognize in the poor Christ Himself. In the Acts of the Apostles, we read that the Apostle Peter said to the cripple who was begging alms at the Temple gate: “I have no silver or gold, but what I have I give you; in the name of Jesus Christ the Nazarene, walk” (Acts 3,6). In giving alms, we offer something material, a sign of the greater gift that we can impart to others through the announcement and witness of Christ, in whose name is found true life. Let this time, then, be marked by a personal and community effort of attachment to Christ in order that we may be witnesses of His love."
You cannot serve God and mammon. (Luke 16:13)
For you know the gracious act of our Lord Jesus Christ, that for your sake he became poor although he was rich, so that by his poverty you might become rich. (2 Cor 8:9)
Now, however, I am going to Jerusalem to minister to the holy ones. For Macedonia and Achaia have decided to make some contribution for the poor among the holy ones in Jerusalem; they decided to do it, and in fact they are indebted to them, for if the Gentiles have come to share in their spiritual blessings, they ought also to serve them in material blessings. (Rom 15:25-7)
If someone who has worldly means sees a brother in need and refuses him compassion, how can the love of God remain in him? (1 Jn 3:17)
But when you give alms, do not let your left hand know what your right is doing, so that your almsgiving may be secret. And your Father who sees in secret will repay you. (Matt 6:3-4)
In every way I have shown you that by hard work of that sort we must help the weak, and keep in mind the words of the Lord Jesus who himself said, 'It is more blessed to give than to receive.' (Acts 20:35)
He sat down opposite the treasury and observed how the crowd put money into the treasury. Many rich people put in large sums.
A poor widow also came and put in two small coins worth a few cents.
Calling his disciples to himself, he said to them, "Amen, I say to you, this poor widow put in more than all the other contributors to the treasury.
For they have all contributed from their surplus wealth, but she, from her poverty, has contributed all she had, her whole livelihood." (Mark 12:41-4)