"While you are at Hogwarts, your triumphs will earn you house points, while any rule-breaking with lose house points. At the end of the year, the house with the most points is awarded the house cup, a great honour."
—Professor Minevra McGonagall explains the house point system and the House Cup.[src]
The House Cup is a yearly award at Hogwarts. It is given at the end of the school year to the House with the most House points. Points are given to Houses by teachers and prefects throughout the year for various things including answering questions correctly and doing good deeds. The winner of the Quidditch Cup also receives points. Points can be taken away for things such as misbehaving. Harry, Ron, and Hermione each lose 50 points for roaming around at early morning.
The House Cup marks an important development of tone in the series. It is of considerable importance in the first book, with Harry feeling devastated to have put Gryffindor in last place after being caught out of bed. With each proceeding book, it is pushed further into the background (the winner not even being revealed after book 3), paralleling the main characters maturing and caring about more important issues.