People can express love towards things other than humans; this can range from expressing a strong liking of something, such as "I love popcorn" or that something is essential to one's identity, such as "I love being an actor".

People can have a profound dedication and immense appreciation for an object, principle, or objective, thereby experiencing a sense of love towards it. For example, compassionate outreach and volunteer workers' "love" of their cause may sometimes be born not of interpersonal love but impersonal love, altruism, and strong spiritual or political convictions.

People can also "love" material objects, animals, or activities if they invest themselves in bonding or otherwise identifying with those things. If sexual passion is also involved, then this feeling is called paraphilia.

Interpersonal love refers to love between human beings. It is a much more potent sentiment than liking a person. Unrequited love refers to feelings of love that are not reciprocated. Interpersonal love is most closely associated with interpersonal relationships. Such love might exist between family members, friends, and couples. There are several psychological disorders related to love, such as erotomania.

Throughout history, philosophy and religion have speculated about the phenomenon of love. In the 20th century, the science of psychology has studied the subject. The sciences of anthropology, neuroscience, and biology have also added to the understanding of the concept of love.
Biological models of sex tend to view love as a mammalian drive, much like hunger or thirst. Helen Fisher, an anthropologist and human behavior researcher, divides the experience of love into three partly overlapping stages: lust, attraction, and attachment. Lust is the feeling of sexual desire; romantic attraction determines what partners find attractive and pursue, conserving time and energy by choosing ; and attachment involves sharing a home, parental duties, mutual defense, and in humans involves feelings of safety and security. Three distinct neural circuitries, including neurotransmitters, and three behavioral patterns, are associated with these three romantic styles.

Lust is the initial passionate sexual desire that promotes mating, and involves the increased release of hormones such as testosterone and estrogen. These effects rarely last more than a few weeks or months. Attraction is the more individualized and romantic desire for a specific candidate for mating, which develops out of lust as commitment to an individual mate form. Recent studies in neuroscience have indicated that as people fall in love, the brain consistently releases a certain set of chemicals, including the neurotransmitter hormones dopamine, norepinephrine, and serotonin, the same compounds released by amphetamine, stimulating the brain's pleasure center and leading to side effects such as increased heart rate, reduced appetite and sleep, and an intense feeling of excitement. Research indicates that this stage generally lasts from one and a half to three years.

Since the lust and attraction stages are both considered temporary, a third stage is needed to account for long-term relationships. Attachment is the bonding that promotes relationships lasting for many years and even decades. Attachment is generally based on commitments such as marriage and children, or mutual friendship based on things like shared interests. It has been linked to higher levels of the chemicals oxytocin and vasopressin, to a greater degree than …

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Greek distinguishes several different senses in which the word "love" is used. Ancient Greeks identified three main forms of love: friendship or platonic desire (philia), sexual or romantic desire (eros), and self-emptying or divine love (agape). Modern authors have distinguished further varieties of romantic love.

Agape (ἀγάπη agápē) Agape, often a Christian term, denotes a form of love that stands apart from the conventional understanding of affection. Rooted in theological discourse, agape represents a love that is characterized by its spontaneous nature and its independence from the inherent value of its object. Originating from the Greek term for "love", agape has been examined within theological scholarship, particularly in contrast to eros. In the Christian tradition, agape is often attributed to the love of God for humanity, as well as humanity's reciprocal love for God and for one another, often termed as brotherly love. Agape is considered to be unmerited and unmotivated by any inherent worthiness in its recipient. Instead, it is portrayed as an expression of the nature of God, exemplifying divine love that transcends human comprehension.

Eros (ἔρως érōs) Eros originally referred to a passionate desire, often synonymous with sexual passion, reflecting an egocentric nature. However, its modern interpretation portrays it as both selfish and responsive to the merits of the beloved, thus contingent on reasons. Plato, in his Symposium, argued that sexual desire, fixated on physical beauty, is inadequate and should evolve into an appreciation of the beauty of the soul, culminating in an appreciation of the form of beauty itself. In Greek mythology, Eros symbolizes the state of being in love, extending beyond mere physical sexuality (referred to as "Venus"). Unrestrained Venus can reduce individuals to mere appetite, but when Eros is present, the focus shifts to the beloved, elevating intimacy beyond physical gratification. Eros is depicted as divine yet potentially dangerous, capable of inspiring both altruism and selfishness.

Philia (φιλία philía) Philia originally describing an affectionate regard or friendly feeling, extended to relationships like friendship, family members, business partners, and one's nation. Similar to eros, philia is often seen as responsive to positive attributes in the beloved. This similarity has led scholars to think whether the primary difference between romantic eros and philia lies solely in the sexual dimension of the former. The distinction between the two becomes more complex with attempts from scholars to diminish the importance of the sexual aspect in eros, contributing to a nuanced understanding of these forms of love. Philia was articulated by Aristotle in his Nicomachean Ethics. Aristotle suggests that philia can be motivated by considerations for either one's own benefit or the benefit of the other. Philia often arises from the utility found in the relationship or from admiration for the character or virtues of the other individual. Aristotle further elucidates that the foundation of philia rests on objective grounds; individuals must share similar dispositions, refrain from holding grudges, and embody qualities such as justice, among others.
In Latin, friendship was distinctly termed amicitia, while amor encompassed erotic passion, familial attachment, and, albeit less commonly, the affection between friends. Cicero, in his essay On Friendship reflects on the innate human tendency to both love oneself and seek out another with whom to intertwine minds, nearly blending them into a singular entity. This suggests that while fri…

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