In general use, a tithe means to pay a voluntary contribution in support of a Jewish or Christian religion. Modern tithes are almost always paid as cash, whereas historically they were paid with agricultural products, animals, or work. Some countries-notably some in Europe-have a legal tithe system in place alongside of their tax system. In the US, paying tithes is a voluntary though expected part of many religions.
Tithes are supposed to be 10% of your gross income though as with everything involving religion and money this is sometimes debated. Paying tithes not only gives you the good feeling of doing what’s right but even better-tithing payments are tax deductible.