Although most of us consider the Sun a star, in Astrology, it’s considered a planet -- and one of the most influential at that. Each month, the Sun moves into a different sign of the zodiac, marking anyone born during that period as an “Aries,” “Taurus,” “Gemini,” etc. So, when someone asks "what's your sign?," they're talking about your Sun sign. While so many other planets determine your personality, it’s the Sun that most heavily shapes your character and the general mood in the air.
The horoscope sign the Sun is in when you’re born predicts a lot, including your general purpose in life. For example, Libra is about balance and strong partnerships, Sagittarius is about philosophy and spirituality and Aquarius loves technology and serving the greater good. You can look to your Sun sign to see where your interests lie -- both professionally and personally.
The Sun also sheds light on your general tendencies. Although your Moon sign better predicts your emotional reactions, your Sun sign often dictates how you behave. Let’s say you get in an argument with your partner. If you’re a fiery, impulsive Aries, you might be quick to say something you’ll regret later, then defer to your independent streak until it all blows over. If you’re a more sensitive Cancer, you might withdraw, consider how the argument affects you on a deeper level and wait for an apology. As an analytic, reserved Virgo, you might not want to express your feelings ... but you’ll definitely want to explain and rationalize them!
In Astrology, the planets move through the zodiac at their own pace and interact with each sign -- and each other -- to set the mood here on Earth.