Canon Law of the Catholic Church concerning fasting and abstinence for Latin Rite Catholics states:
Can. 1249 All members of the Christian faithful in their own way are bound to do penance in virtue of divine law; in order that all may be joined in a common observance of penance, penitential days are prescribed in which the Christian faithful in a special way pray, exercise works of piety and charity, and deny themselves by fulfilling their responsibilities more faithfully and especially by observing fast and abstinence according to the norm of the following canons.
Can. 1250 All Fridays through the year and the time of Lent are penitential days and times throughout the universal Church.
[Although no particular penance is prescribed by the Church (ref Can. 1250), the old discipline of abstinence on all Fridays and of fasting on all weekdays of Lent may be maintained. If not, it must be replaced by some other form of penance.]
Can. 1251- Abstinence from eating meat or another food according to the prescriptions of the conference of bishops is to be observed on Fridays throughout the year unless they are solemnities; abstinence and fast are to be observed on Ash Wednesday and on the Friday of the Passion of the Death of Our Lord Jesus Christ. [Whenever a solemnity (first class feast) falls on a Friday, abstinence is dispensed.]
Can. 1252- All persons who have completed their fourteenth year are bound by the law of abstinence; all adults are bound by the law of fast up to the beginning of their sixtieth year. Nevertheless, pastors and parents are to see to it that minors who are not bound by the law of fast and abstinence are educated in an authentic sense of penance.
Can. 1253- It is for the conference of bishops to determine more precisely the observance of fast and abstinence and to substitute in whole or in part for fast and abstinence other forms of penance, especially works of charity and exercises of piety.
[In the United States and many other countries the days of abstinence are Ash Wednesday and all Fridays of Lent. On other Fridays, one is allowed to commute abstinence into another form of penance (e.g., the Way of the Cross).]