The Moon has the same level of impact as the Sun in the natal chart. The Sun side in you reflects what you want others to see in you, or what you let them to, but the Moon part is the true you, the part of you that is visible for you only. The Moon is the symbol of your inner thoughts, emotions and intuitive reactions. In other words - your emotional experience, based on the events in your life and how they've affected you.
The Moon's range of influence includes: mood, emotional and physical changes, your emotions and expectations, little things like your habits or preferences ( not global), sense of style and unconscious choices of yours when you had no time to think over something or to decide it properly. If you have ever done something that is nothing about your style and then thought that it didn't look like you at all - it is the manifestation of the Moon. Pay attention to the sign where the Moon is in - it represents your hidden true desires and ways to keep you happy in this period of life. The Moon's sign reflects the thing you need most right now.
Often you will be the only person, who knows your Moon personality, but some people can see it in you, if you let them. It is your subconsciousness, desires that you reject, feelings that you avoid and thoughts that haunt you. Also it shows your personality through spontaneous situations full of joy and excitement. The Moon in your horoscope changes your Zodiac sign a little bit, providing new directions and another point of view on life. For instance, a Gemini-Sun person with Moon in Taurus will be more attached to another person than a Gemini-Sun with Moon in Aquarius. That's why we often can't fully determine a person's image, having only his\her Sun.
The Moon was always a symbol of femininity in people. It is often connected with mother and with other women in total. If it is a man's chart the Moon will point the perfect woman-partner for a certain man. Venus indicates on something similar, but more in romantic context, while the Moon implies deeper and longer relationship.
The Moon always grows and shrinks, from new Moon to full Moon and starts the cycle again. The Moon in your natal chart will show your most vulnerable and sensitive area of life. It is the most unstable area of your life, so it regularly changes.