Going back to the work of Abraham Maslow, behavioral scientists have found lots of evidence for the importance of love in one's life.

Feeling unloved is, just as Maslow suggested, a wretched feeling that stunts growth and happiness.

Finding love, which comes in all kinds of varieties, is, without question, an essential part of the human lived experience.

• People differ widely in how they understand what love is. Most ideas of love center on mutuality, pleasantness, and low conflict.

• One concept of love, the ancient word "agape," is given less attention, including in psychological research, than the other kinds of love.

• Agape is defined and its paradox discussed: As you are in service to another, despite your own pain, you benefit as may your relationship.

• People use the word "love" to describe a variety of forms of affection — from "loving" one's favorite snack to "loving" a romantic partner.

• Other words describe different types of love, such as "eros," which describes erotic love, or "ludus," which focuses on playful flirtation.

• Terms that describe types of love also include "pragma," or pragmatic, mature love, and "philia," which describes friendship and mutual respect.

• Love involves some combination of intimacy, passion, and commitment.

• Cross-cultural research provides evidence that these components are universal.

• Of all the people in the world, there is likely just a handful at most in your lifetime with whom you will fall in love.

Love, at its true core, is a moment-to-moment emotional experience of warmth and mutual caring.

Real love is “shared positivity.” This occurs anytime two people connect over a shared positive emotion.