All birth charts contain all 12 houses, although you may not have a particular aspect (planet) in that house. But in every birth chart every sign is included because one of those signs rules a certain house in your birth chart whether you have planets there or not.
There are keywords associated with having certain planets or signs in the third house, however certain aspects between other placements in your birth chart and the evolution of that aspect make all the difference. These are just basic facts about each Placement in the third house.
Communication, transportation, and local community are all governed by the third house. Natal planets in the Third House are motivated by expression and often help guide you to build close relationships with your peers, including siblings, coworkers, and classmates. The third house of a natal chart is traditionally ruled by the zodiac sign Gemini and its ruling planet Mercury.
Where is your Third House located?
Aries: you're eager to learn new things, but you have trouble sticking with anything long enough to really learn it. You can be mentally aggressive, prone to arguments and defending your ideas, and short-tempered, so you need to make sure you have an outlet for the excess energy to prevent periodic explosions.
Taurus:When you dedicate yourself to learning something, you’ll stick with it until you’ve got it, no matter how long it takes, and you’ll remember it for the rest of your life. Learning could be easier for you when you involve your senses, and you can take in knowledge using what you see, hear, smell, taste, and touch to help you. Playing soft music while studying or trying to absorb something new could help as well.
Gemini: Gemini is the natural ruler of the 3rd house, so having Gemini here denotes you have a mind that is naturally quick and an ease in communication. You require mental stimulation, love conversation with others, are a social person, and can take in facts easily. You have an easy time dealing with the small details, but can struggle with the bigger picture and large projects. You’re open to new ideas, and understand different modes of thought. While your mind moves quickly, it can be too quick at times, and when that happens, you can have a hard time communicating effectively.
Cancer: You never forget the emotions you felt and that coursed through others in any given situation. While this makes you understanding, it can also make it hard for you to be objective. Learning may have been difficult for you as a child, and it makes you sensitive when it comes to learning as an adult. If you have siblings, they likely played an important role in your childhood.
Leo: Your mind is creative, and you enjoy gossiping, joking around, and having a good laugh. You can be surprisingly stubborn when it comes to your thoughts, and need to learn to be more open to other people’s opinions. Words can wound your pride, and when someone cuts you in this way, it runs deep and perhaps forever.
Virgo: You have a strong mind centered around logic and reason, and you need to learn to feed your mind. You’re excellent with the details, practical, and able to dedicate yourself to any mental work required of you. You can be critical of other people’s opinions, or of your siblings or neighbors.
Libra: You can charm people with your words, talk people into compromising and finding middle ground no matter how much they resist, and you’re not forceful or demanding. You avoid conflict and arguments, wanting everyone to get along. Without mental balance and harmony, you feel off in life.
Scorpio: You can dominate other people, are intense in your communications, and overwhelm others. Words can help you transform in life, or you can use your words to help transform others. You’re researching and won’t stop digging into something until you’ve gotten to the core. When something interests you, you can become obsessed with it. You can be too judgmental, and may feel that people should do whatever you tell them to.
Sagittarius: You’re interested in learning about the world, worldly issues, and look at the big picture, but the details can escape you. You love to learn, but can do better learning on your own. You want to expand your mind whenever you get the chance, and enjoy exposing yourself to new cultures and ways of living. When you talk, you do so in a big way, and are an excellent storyteller. You’re also quite honest.
Capricorn: You try to only say what needs to be said, and don’t waste your time on anything else. If you don’t have something productive say, you won’t say anything at all. You may seem quiet or secretive as a result. Learning or getting an education may have been difficult when young for some reason, and as you get older, you take studying seriously, and can use it to help you achieve your goals.
Aquarius:You’re open to new modes of thoughts, new ways to express yourself, original ideas, and are forward-thinking. You may not have patience for anyone who isn’t the same way as you though, and need to not be so critical of people who aren’t as open or unique. You can speak before you take the time to say anything, and this can put you in situations you don’t want to be in.
Pisces: Your emotions can cloud your judgment, and they prevent you from being able to communicate. This is usually a problem in your youth. As you evolve, you become more creative, intuitive in your communications, and can see through what people say to what they really mean. You come up with your best ideas on your own, and require a certain amount of time alone to recharge your mind.