Cancer
Cancer is the zodiac sign for people born between June 21 and July 22. Element: water; modality: cardinal; ruling planet: the Moon. The cusp dates shift by a day from year to year, so if you were born near a cusp, check your sign with the calculator.
Personality
Cancer is the sign of home, memory and attachment. Cancers create a space where people feel safe and look after their own before themselves. The soft exterior is deceptive: in defending loved ones, Cancer is stubborn and persistent.
Strengths: sensitivity, loyalty, a memory for what matters, the ability to support others.
Weaknesses: touchiness and withdrawal. Instead of talking about a problem, Cancer shuts down and waits for others to guess the reason; they hold on to grudges long after making up.
The Gemini man and woman
The Cancer man is caring, a homebody and emotionally perceptive; he needs to be sure he won't be abandoned.
The Cancer woman is the keeper of home and family; she becomes deeply attached and finds it hard to let go.
Career and money
Work connected with care, home and history suits them: medicine, education, psychology, hospitality, cooking, real estate, archives.
Cancer treats money as security: they save for a rainy day and spend on the home and on loved ones.
Compatibility
Traditionally, the easiest matches are signs of the same element and of compatible elements; for Cancer these are Taurus, Virgo, Scorpio and Pisces.
The most challenging are signs in square and in adjacent positions: Aries, Gemini, Leo and Libra. The opposite sign is Capricorn: strong attraction and an equally strong struggle.
These are general rules of aspects, not a verdict. Each pair is covered separately in zodiac compatibility.
The sign in the birth chart
Your Sun sign is just the position of the Sun at the moment of birth. A full birth chart also includes the sign of the Moon (emotions), the Ascendant (first impression) and the positions of the other planets.
That's why a person may "not seem like an Aries": they have an Aries Sun, a Cancer Moon and a Libra Ascendant, and what comes across is nothing like a Martian manner. Horoscopes in the media work only with the Sun sign, hence the feeling that they aren't about you.