Ash Wednesday and Good Friday are obligatory days of fasting and abstinence for Catholics. In addition, Fridays during Lent are obligatory days of abstinence.
For members of the Latin Catholic Church, the norms on
A Reflection on Lenten Fasting
If possible, the fast on Good Friday is continued until the Easter Vigil (on Holy Saturday night) as the "paschal fast" to honor the suffering and death of the Lord Jesus and to prepare ourselves to share more fully and to celebrate more readily his Resurrection.