The Moon's Importance
The moon has an important role in the Earth's existence. The eight phases of the moon, the tides, and eclipses all play an important role today.
Phases of the moon:
We all know the moon has eight phases. This is important, you know. The Moon's phases help us make, and keep track of calendars. It also shows how far into the month you are when you are away form technology. They effect us here on earth, too. Lets say it's a waning crescent out tonight, the Moon's light would not be as bright as it would be on a full moon night.
Tides also play a big role. Without tides, all water would be equal around all surfaces of the Earth. This could be bad. If water did not evaporate quick enough, floods would occur more often. Tides regulate water flow so this doesn't happen. This is one of the reasons tide-pools occur.
(Solar and Lunar)
We all know what an eclipse is. There are two types of eclipses, solar and lunar. Solar eclipses happen when the moon is between the path of the Sun and the Earth. The moon blocks the Sun's light from reaching Earth. Solar eclipses only occur on a new moon.A lunar eclipse is when the Earth is in the path of the Sun and the Moon. The Earth blocks the light from the Sun from reaching the Moon. Lunar eclipses only occur on a full moon. They affect the Earth because solar eclipses block vital sunlight, if only for a few seconds. Lunar eclipses affect the Earth because it blocks the Moon's reflection source, so it'd be hard to see at night (not counting artificial light sources).
Without the moon, our world fall into chaos, tides wouldn't exist, we wouldn't know what time it was, and we wouldn't be able to see during the night without an artificial light source. Those are only a few reasons, and I'm sure that there are plenty others. Without the moon, we would need way more advanced technology to be able to survive on Earth until daylight.