In astrology, the three central components of a chart are the placement of the Moon, Sun, and Ascendant (also known as Rising sign.) In a natal chart, the Sun and Moon can be in any House, in any sign. Our Ascendant can be in any sign, too, but it's always in the First House.
You've probably heard the phrase "What's your sign?" This person would be asking about your Sun Sign. From our viewpoint on Earth, the Sun travels around us once each year--spending one month in each of the 12 signs of the Zodiac. The sign that the Sun was traveling through at the time of your birth is your Sun sign. For example, I was born on November 6th, so my Sun sign is Scorpio. Our Sun sign is where we feel the urge to express ourselves--our individuality. It's who we are at our core--raw and unvarnished. The Sun is also associated with the Father/masculine energy, leaders and authority figures, and the 5th House. In an astrological chart, the symbol for the Sun is a circle with a dot in the middle.
The Moon sign is the less conscious part of our personality. In her insightful book Mapping Your Birthchart: Understanding Your Needs & Potential author Stephanie Jean Clement has this to say about the Moon: "Its position in the birthchart can tell a lot about where your emotional stress comes from, and how you react instead of consciously responding to events and situations. The Moon is also where you find information about how you assimilate and store information---about how you learn and about how your memory functions. The Moon represents the feminine in a chart (along with Venus). The maternal instinct, in both men and women, is seen through the Moon's positions, along with emotional traits in general...In any astrological chart the Moon represents the action. In a person's chart the Moon indicates how that individual instinctually acts, and it further indicates how events will unfold...(and) indicates the means we use in our daily activities. We have one type of individuality, indicated by the Sun, and often a quite different method for accomplishing our goals." The Moon is also associated with the 4th House. In an astrological chart, the symbol for the Moon is a crescent Moon.
The Ascendant (ASC), also known as the Rising sign, is the face we present to the world. It is associated with the 1st House of ego and persona. The Ascendant is one of two chart elements that are determined solely by the place and time of birth, which makes it a very personal point in a chart (the other being the Midheaven). The Ascendant is the "mask" we wear, and indicates the type of character we generally play on the stage of life. It also indicates how we show ourselves to others...and what we choose to show. However, because it's a mask of sorts, it can also color the way we see the world. In the book Choice Centered Astrology: The Basics author Gail Fairfield says that "The Sign on the Ascendant represents the qualities that were most reinforced by your whole extended family system."