Your moon sign is the sign the Moon occupied at the moment you were born. Where the Sun describes what you are deliberately building, the Moon describes what you do before you have decided anything: how you settle yourself, what you reach for when the day has gone badly, and what has to be true for you to feel safe in a room.
Enter your birth date, birth time if you have it, and birth city, and the reading returns your moon sign with an interpretation written against the actual calculated position, not a lookup table of birth months.
The Moon travels roughly thirteen degrees a day and changes sign about every two and a half days. That is fast enough that a birth near a sign change can land either side of the boundary depending on the hour. If you were born within a day of a cusp, the birth time is the difference between two entirely different readings, which is why we ask for it and why we say so when it is missing.
Birth city matters for the same reason: the calculation runs on universal time, so the local time you were told has to be converted using the correct historical time zone and daylight saving rule for that place and year. Getting that wrong shifts the whole chart.
The Moon governs habit, memory, appetite, and reflex. In a chart reading it answers a narrow set of questions well: what soothes you, what you consider ordinary care, how quickly you recover from a shock, and what kind of attention feels like love rather than pressure.
It answers other questions badly. It will not tell you your career, your compatibility with a specific person, or what happens next week. Any reading that promises those things from one placement is overselling a single data point.
Two different things share the word moon. The phase is the relationship between the Sun and Moon at your birth, a new moon birth versus a full moon birth. The sign is which twelfth of the zodiac the Moon occupied. This reading covers the sign. The phase is a separate layer and is included in the full natal chart report.
Birth date, time, and city are stored only to generate and regenerate your reading and any chart you ask for. They are never sold and never handed to advertisers. You can ask for deletion at any time through the contact page.