Loyalty is faithfulness or a devotion to a person or cause.
Loyalty evolved as devotion for one's family, gene-group and friends. Loyalty comes most naturally amongst small groups or tribes where the prospect of the whole casting out the individual seems like the ultimate, unthinkable rejection. Loyalty to tribes evolved from the evolutionary tactic that there is a greater chance of survival and procreation if animals form packs/tribes
In a feudal society, centered on personal bonds of mutual obligation, accounting for precise degrees of protection and fellowship can prove difficult. Loyalty in these circumstances can become a matter of extremes: alternative groups may exist, but lack of mobility will enter a personal sense of loyalty.
The rise of states (and later nation states) meant the harnessing of the "loyalty" concept to foster allegiance to the sovereign or established government of one’s country, also personal devotion and reverence to the sovereign and royal family.
Wars of religion and their interminglings with wars of states have seen loyalty used in religious senses too, involving faithful support of a chosen or traditional set of beliefs or of sports representatives. And in modern times marketing has postulated loyalties to abstract concepts such as the brand. Customer churn has become the opposite of loyalty, just as high treason once stood as the opposite of the same idea. Compare loyalty card
Loyalty is also seen in business in a variety of ways. As governments have grown in size and scope, some people are more loyal to a company rather than to a country. As corporation complexity has grown, people have shifted their loyalties to individuals rather than companies. As those individuals move between companies, they often take other people with them. Stock options are one method devised to keep people loyal to a company.
The concept of loyalty is an important part of sex. Plato originally said that only a man who is just can be loyal, and that loyalty is a condition of genuine philosophy. The philosopher Josiah Royce said it was the supreme moral good, and that one's devotion to an object mattered more than the merits of the object itself.