Answer:
There's the life line which starts near thumb and arches downward towards or to the wrist. It reflects your life and how it's lived. The head line starts near or with the life line (if it's the latter, they'll split apart eventually) and runs horizontally across your palm ( at a slight, or outright angle or bend). It reflects your mind, how you think, and where you apply your thoughts. There's the heart line which is the highest main line on your palm that runs from the outside of your palm (pinky side) to the inside (towards the index finger). This line represents your relationships with people, how you view romance (or if you do at all), how your love life will be, and what kind of people you get along with (since it throws other people into the mix, you should never time this line). And finally, the fate line, it runs vertically from the wrist towards your fingers. It defines your purpose on this earth, what you'll do for a living, and how prosperous you'll be. If any of these lines are absent ( I don't think it's possible to not have a life line since it's the very fist line formed in the womb) it's very bad. If you have no head line, you're bound to fall into insanity, no fate line, you're at the utter mercy of what ever life sends your way and you'll never have any direction on what to do with your life, and for the heart line, you'll be a ridiculously lonely and cold person (I could be wrong about the heart line, I'm not too sure). Those are the four lines in main lines. There are many others of lesser significance and not everybody has them.