The tithe is a tenth of our income that we give to the work of the Lord. The first mention of the tithe is in Gen 14:18 - 20 where Abraham gave a tithe to Melchizedek the priest. The Law of Moses establishes the giving of the tithe in Lev 27:30-32.
In the New Testament, the Lord Jesus mentions the tithe as something that we should continue along with the other important duties of the law such as justice, mercy and faithfulness (Matt 23:23). The Apostle Paul further mentions that our attitude towards giving should be cheerful and generous (2 Cor 9:6-13).