Alms are material goods which are given to the poor as an act of mercy, charity, or kindness. The practice of almsgiving is a very important feature of many religions; in Islam, for example, the giving of alms is one of the five pillars of Islam, the fundamental deeds which all faithful Muslims must perform. Outside of religion, many cultures have a general commitment to kindness and charity, recognizing that the needy should not be ignored by people of good character.
In some religions, the need to give alms is explicitly spelled out, as in Islam. In other instances, such as Christianity, people are not required to give alms, but almsgiving is generally expected. A Christian who does not contribute to charity might be viewed with suspicion by fellow Christians, as they would perhaps doubt that person's Christian virtue. Socially, wealthy people are often expected to contribute to charity, under the argument that no one person could possibly use up an entire fortune.
Alms can take a number of forms. Sometimes, alms are simply cash donations, but they can also take the form of food, shelter, clothing, tools, and more intangible assistance, like job training, medical care, and continuing education programs. Many religious organizations use the alms they collect to support their religious charities, offering things like healthcare for children and housing for the homeless, and people may chose to donate to such organizations so that their charity has a larger impact by being pooled with the donations of others.
In Buddhism, alms are given to monks and nuns by laypeople, and it is less an act of charity than an act of connection with the faith. In some Buddhist sects, monks and nuns are expected to maintain themselves entirely on alms, sometimes making daily rounds for donations of food, and they may be explicitly forbidden from accepting money. Some Christian monks and nuns also use alms as a form of support in much the same way, with laypeople supporting the religious life pursued by people who choose a monastic life.
One certainly does not have to be religious to give alms, and charity of some form is an important part of secular life. Alms also doesn't necessarily have to benefit the human poor; people who care about animals, for example, could choose to give charity to organizations which help animals, or alms could be used to support the work of organizations which protect the environment. Offering charity is often cited as an important part of someone's life by people who engage in charity, as they feel that it gives them a chance to give back to their communities and to support general improvements in the quality of life for everyone.