Do We Fast on Sundays in Lent?

Here is what the United States Conference of Catholic Bishops (USCCB) has to say on the matter of fasting during Sundays in Lent:

Apart from the prescribed days of fast and abstinence on Ash Wednesday and Good Friday, and the days of abstinence every Friday of Lent, Catholics have traditionally chosen additional penitential practices for the whole Time of Lent. These practices are disciplinary in nature and often more effective if they are continuous, i.e., kept on Sundays as well. That being said, such practices are not regulated by the Church, but by individual conscience.