Anywhoo. My father-in-law told me a Catholic must abstain from meat every day of Lent. A friend said on every Friday of the year we were to abstain from meat. So, I went to my friendly neighborhood (well, web-wise) site, Catholic.com, to find answers.
At Lent, we abstain from meat on Fridays. It used to be on Wednesdays too, but not anymore. Of course we're free to give it up more often. Read the Q and A about that here.
At times other than Lent, we're still supposed to treat Fridays as special. It's the "chief day of penance." The law of abstinance from meat is binding unless the local bishops say otherwise. In the United States, the bishops have permission from the Vatican to allow a substitution for the no meat thing. So, we may choose the form of penance we wish to do. I think this makes sense. For a lot of people not eating meat isn't a big sacrifice. Skipping a cup of coffee or giving up your daily Facebook is a better choice. Remember, this is for NON-Lent Fridays and the the U.S.A. (I haven't read the guidelines for other countries.) You still must give up meat on Lenten Fridays. Please read Jimmy Akin's answer for the complete answer to this.