On July 30, 2018 Father-in-Law Day is celebrated. This is a special day to show your appreciation to your father-in-law. A parent-in-law is a person who has a legal affinity with another by being the parent of the other's spouse. It is assumed that the greeting card industry is the originator of this day like its counterpart the Mother-in-Law Day. Since your father-in-law is the man who has brought up your spouse well and healthy you can show him your appreciation by spending time with him, sending him a greeting card or gathers the whole family and celebrates a party in his honor.