The phrase 'Over the Moon' means extremely pleased and happy.
You can use the phrase 'Over the Moon' when describing your feeling when something great had happened to you.
Example of Use: "When he sent me flowers and a note, I was over the moon."
Though the phrase is still popular today, particularly in British Football, the origin of the idiom 'over the moon' has its roots in the early 1700s. One of the first allusions to 'over the moon' in print can be seen in Charles Molloy’s 1718 work 'The Coquet', or, 'The English Chevalier': “Tis he! I know him now: I shall jump over the Moon for Joy!”