The 3rd house, ruled by Gemini, contains your siblings, education, communication, transportation, and self-expression. It helps you to open your mind to a variety of new ideas, then to mold those thoughts into a form that can be expressed in the world. The 3rd house represents ideas and metal acuity. It provides hints about how you speak and how you learn.
Read the sign on the cusp of your 3rd house to provide information about how you get your ideas across to the world. For example, a Cancer 3rd house cusp may speak in words that express feelings and emotions, whereas a Sagittarius cusp may speak in broad, altruistic, and philosophical concepts.
The 3rd house also represents communication and travel that happen quickly, such as a one-day workshop, writing a magazine article, or taking a short weekend trip.
The 3rd house can also tell you about your brothers and sisters, since they're how you learned to communicate in the first place. It can also give you hints about the car you drive: a Leo 3rd house cusp, for example, may want to drive a showy luxury car!
This is one of the places in the chart to look at the nervous system, respiratory ailments, asthma, and communications problems like stuttering.