Short answers, pulled from the story.
The Investiture Controversy was a medieval dispute between secular rulers and the papacy over the appointment of bishops and abbots. It began when Holy Roman Emperors appointed church officials to maintain imperial authority despite church doctrine reserving this task for clergy alone.
Pope Gregory VII first excommunicated Henry IV in 1076 after the king continued appointing his own bishops. The pope excommunicated Henry IV again on the 7th of March 1080 during the Lenten synod following a council that declared Gregory illegitimate.
Henry IV traveled to Canossa in northern Italy where the Pope stayed in the castle of Countess Matilda. This event became known as the Road to Canossa and involved the pope standing barefoot in the snow as penance for his sins before lifting the excommunication.
The Concordat of Worms ended the conflict on the 23rd of September 1122 near German city of Worms between Pope Callixtus II and Holy Roman Emperor Henry V. It eliminated lay investiture while allowing secular leaders some room for unofficial but significant influence in the appointment process through the granting of a scepter symbolizing temporal power.
The controversy weakened emperor authority and strengthened local separatists leading to increased serfdom and reduced rights for the majority. Localized rights of justice emerged where courts did not answer to royal authority causing royal coffers to decline and Germany to lose intellectual leadership in western Europe.