Morning is either the period from sunrise to noon, or the period from midnight to noon. In the first definition it is preceded by the twilight period of dawn, and there are no exact times for when morning begins (also true of evening and night) because it can vary according to one's latitude, and the hours of daytime at each time of year. However, morning strictly ends at noon, when afternoon starts.

Morning precedes afternoon, evening, and night in the sequence of a day. Originally, the term referred to sunrise.

The Late Modern English words morning and tomorrow began in Early Middle English as morwening, developing into morwen, then morwe, and eventually morrow. English, unlike some other languages, has separate terms for morning and tomorrow, despite their common root. Other languages, like Dutch, Scots and German, may use a single word – morgen – to signify both morning and tomorrow.

Morning prayer is a common practice in several religions. The morning period includes specific phases of the Liturgy of the Hours of Christianity.

Some languages that use the time of day in greeting have a special greeting for morning, such as the English good morning. The appropriate time to use such greetings, such as whether it may be used between midnight and dawn, depends on the culture's or speaker's concept of morning. The use of good morning is ambiguous, usually depending on when the person woke up.

Many people greet someone with the shortened "morning" rather than "good morning". It is used as a greeting, never a farewell, unlike good night which is used as the latter. To show respect, one can add the addressee's last name after the salutation: "Good morning, Mr. Smith."

For some, the word morning may refer to the period immediately following waking up, irrespective of the current time of day.^{[citation needed]} This modern sense of morning is due largely to the worldwide spread of electricity, and the independence from natural light sources.^{[failed verification]}

When a star first appears in the east just prior to sunrise, it is referred to as a heliacal rising. Despite the less favorable lighting conditions for optical astronomy, dawn and morning can be useful for observing objects orbiting close to the Sun. Morning (and evening) serves as the optimum time period for viewing the inferior planets Venus and Mercury. Venus and sometimes Mercury may be referred to as a morning star when they appear in the east prior to sunrise. It is a popular time to hunt for comets, as their tails grow more prominent as these objects draw closer to the Sun. The morning (and evening) twilight is used to search for near-Earth asteroids that orbit inside the orbit of the Earth. In mid-latitudes, the mornings near the autumnal equinox are a favorable time period for viewing the zodiacal light.