From the Code of Canon Law of 1917, with the modifications:
Approved in 1949
~ (complete) abstinence only is to be observed on all the Fridays throughout the year
~ Fast and (complete) abstinence is to be observed on Ash Wednesday, the Fridays of Lent, Ember Fridays, the Vigils of the Assumption and Christmas, and Holy Saturday
~ Fast only (and partial abstinence) is to be observed on: all weekdays of Lent, Ember Wednesdays and Saturdays, and the Vigils of Pentecost and All Saints
~ On the days of fast, only one full meal is allowed
~ Two other meatless snacks, sufficient to maintain strength may be taken according to each one's needs, but together they should not equal another full meal
~ Meat may be taken at the principal meal on a day of fast except on the days of complete abstinence
~ Eating between meals is forbidden, but liquids including milk and fruit juices are allowed
~ On holydays of obligation, except in Lent, there is neither fast nor abstinence
~ The laws of abstinence binds all who have completed their seventh year of age; the law of fasting binds all persons from the completion of their twenty first year until the beginning of their sixtieth. (The completion of the seventh year means the day after the seventh birthday).
versus
According to the 1983 Code of Canon Law
~ All Fridays through the year and the time of Lent are penitential days and times throughout the universal Church
~ Abstinence from eating meat . . . is to be observed on Fridays throughout the year unless they are solemnities
~ abstinence and fast are to be observed on Ash Wednesday and [Good] Friday
~ All adults who have completed their fourteenth year are bound by the law of abstinence
~ all adults [from age 18] are bound by the law of fast up to the beginning of their sixtieth year
~ The Episcopal Conference can modify these general rules
~In the United States Catholics are obliged to abstain from the eating of meat on Ash Wednesday and all Fridays during the season of Lent.
~ They are also obliged to fast on Ash Wednesday and on Good Friday
~ Self-imposed observances of fasting on all weekdays of Lent is strongly recommended
~ Abstinence from flesh meat on all Fridays of the year is especially recommended to individuals and to the Catholic community as a whole
~In Australia, "Abstinence from meat, and fasting, are to be observed on Ash Wednesday and Good Friday
~ On all other Fridays of the year the law of the common practice of penance is fulfilled by performing any of the following:
(a) prayer, as for example Mass attendance, family prayer, . . .
(b) self-denial, e.g. not eating meat, not eating sweets or dessert, . .
(c) helping others, e.g. special attention to someone who is poor, sick, elderly, . . .
Excerpted from the Catechism of Pope St. Pius X