Morning is the earliest part of the day. No matter what time you get up, morning ends at noon.
Originally, in the 13th century, morning meant the time just before sunrise. Now, morning technically starts at 12:00am and lasts until 12:00pm. If you describe yourself as a "morning person," you like to get up early. Strangely enough, a "night person," who stays up very late might not go to bed until several early-morning hours have passed.