Eros is a concept in ancient Greek philosophy referring to sensual or passionate love, from which the term erotic is derived. Eros has also been used in philosophy and psychology in a much wider sense, almost as an equivalent to "life energy". The Protestant philosopher C. S. Lewis posits it as one of the four ancient Greek words for love in Christianity, alongside storge, philia, and agape.

Love encompasses a range of strong and positive emotional and mental states, from the most sublime virtue or good habit, the deepest interpersonal affection, to the simplest pleasure. An example of this range of meanings is that the love of a mother differs from the love of a spouse, which differs from the love for food. Most commonly, love refers to a feeling of strong attraction and emotional attachment.