Nuns in movies and TV often seem to do little but scowl and whack disobedient children with a ruler. In the real world, nuns' duties cover a diverse range. Some nuns devote themselves to prayer and contemplating God, while others help the poor, teach children or care for the sick. One thing all nuns have in common is that they're acting in ways that they believe serve God, not themselves.

What Is a Nun?

Nuns are found in several Christian sects and churches, but most American nuns belong to the Roman Catholic Church. Sixty years ago there were 180,000 Catholic nuns in the United States, but the number at time of writing, the membership has fallen to less than 50,000.

Answering the question, of what is a nun, isn't as simple as it looks. A nun is a woman who devotes herself to a contemplative, spiritual life in a convent. Becoming a nun is a lifelong commitment that involves vows of poverty, celibacy and obedience to God. Most nuns' lives center on the monastery - one of several names for Christian religious communities - and their relationship with God. Some nuns, however, do charitable work such as teaching or nursing outside the convent.

Laypeople also use the term "nun" to refer to what the Catholic Church calls sisters. Sisters also devote themselves to God and the Church but they're more active in the secular world in various ways. The technical difference between the two groups is that nuns take solemn vows, sisters take simple vows. Simple vows aren't any less binding, but they're slightly less restrictive. A solemn vow of poverty requires giving up all worldly goods and possessions. A sister who takes a simple vow can retain ownership of property they inherited from their parents. However they don't get to use their property or pocket any revenue it generates.

To further complicate things, both nuns and sisters are addressed as "sister," such as Sister Joan or Sister Agnes. Nobody should worry about giving offense, if they confuse the two groups. It's perfectly acceptable in casual conversation to refer to sisters as nuns or vice versa. If you encounter a nun outside of a monastery, it's more likely to be a sister, as they're the women most often found in the everyday world.

What Is a Nunnery?

The names of the religious communities that nuns and sisters live in - monastery, convent, abbey, nunnery - can also confuse the uninitiated. Many people think of "monastery," for instance, as a community of men, rather than a community of women. In reality, a monastery is any religious community, male or female, that sets itself apart from the everyday world. They pray, they work within the community, but rarely leave it.

Monasteries originated centuries ago. The first monastics were hermits, living completely apart, often in the desert. Over time, as the number of monastics grew, they began to share common areas for eating and prayer. That evolved into today's reclusive religious communities.

Convents can also be male or female religious communities, although in the 21st century, in the United States, the name gets used almost entirely for women's communities. What makes a convent differ from a monastery is that the religious orders who live in convents are active in the world, rather than contemplative and secluded from the world.

An abbey is simply a name for a large monastery headed by an abbott or an abbess. A nunnery isn't an official church term. It's commonly used by laypeople to refer to convents and female-occupied monasteries. To further muddy the waters, the term "nunnery" has been slang for a brothel since the 1500s.

Choosing a Nun's Life

Becoming a nun is a big deal. You live a life consecrated to God, under the command of the Catholic Church. The goal is to live in imitation of Jesus by professing and following a path of poverty, chastity and obedience. Taking vows, whether complex or simple, changes your life.

Like most things about nuns, becoming one, or becoming a sister, is more complicated than it may look from outside. For starters there's no such thing as a generic, plain nun. Each nun belongs to a religious order such as the Poor Clares, the Missionaries of Charity, the Carmelites or the Benedictines. Becoming a nun or sister requires choosing not only a life of faith but life within a specific order.

The one thing all nuns have in common is that they're serving God. Becoming a nun or a sister isn't a secular career, it's a career God has called them too. Laypeople are sometimes surprised that even attractive women may choose to become a "bride of Christ" over having a home and a family. Or a profitable career: if you've ever asked how much do nuns make, the answer is they make nothing. Becoming a nun or a sister is a spiritual choice, not a paying job.

To start making this choice, pray for God for guidance. Pray with others, pray by yourself and be patient waiting for an answer. Study the Bible for accounts of people who were called to God's service. St. Paul is a classic example: he first appears in the New Testament persecuting the Christian faith until he converts and becomes one of the most prominent early Christians.

If you think this might be the right path for you, talk to nuns, in person or online, about their lives and the pros and cons, spiritual and practical. Talk with family or friends whose judgment you trust, and with your priest. If everything feels right, begin exploring different monastic orders. Different orders and religious communities follow distinctive paths:

• The order's apostolate is the mission that the leaders believe Christ has chosen for them. In a cloistered monastic order,  it may be prayer and contemplation. Other orders help the poor meet their need for food, shelter or medical care. Still others have a spiritual or intellectual apostolate, such as teaching, preaching or counseling. If an aspiring nun doesn't feel called to the apostolate, the order might not be right for her.
  
• The community's rule of life governs every aspect of what they do. The habits that many nuns wear. The nature of their spiritual life. Their apostolate. How meals are taken. How members interact with each other.
  
• The history of the community. Saints from the order or inspirational members who followed the rule give new nuns an example they can emulate.
  
• What is the order's charism? The charism is the way a particular order shares in God's work. It's seen as a gift from God that gives the community its purpose, its motivation, its soul and its driving force. 
  

Even if you find an order that seems to fit your calling, that doesn't guarantee you'll get in. To become a Catholic nun you have to be an unmarried Catholic woman with no dependent children. You need to be at least 18 years old, and in most cases, younger than 40. By the time you become a novitiate nun, you have to be debt free.

Assuming the community fits you and you fit them, you have to complete a series of steps to become a nun. First, as an aspirant, you live in the community on a trial basis, to confirm that you're right for each other. Then you formally move in and become a postulant, a slightly more serious trial basis. If the relationship is still going strong, you enter your novitiate, a period of two years intensive study and prayer. Then come simple vows. Several years later, if you stay the course, you take your solemn or final vows.

What Do Nuns Do?

The simple answer to "What do nuns do?" is that they follow the will of the Church, their order's rule of life, and the directions of their superiors in the order. What that means in terms of day-to-day life depends on the order.

The Sisters of Carmel, for instance, are a cloistered monastic order. They offer themselves to God by living austere lives, staying silent most of the day even among themselves. A Carmelite nun spends eight hours of the day in prayer, two in recreation and five in manual labor or study. Manual labor may include handcrafting items that the order can sell. The order depends on the money that such items bring in, plus donations from believers. The Carmelites hope that their religious devotion will atone, in God's eyes, for the many ways the world falls short.

The Missionaries of Charity, the order founded by Mother Teresa, includes both active and contemplative sisters. The contemplative branch lives a life of fasting, penance and solitude, but they also spend two to three hours a day proclaiming the word of God to the poor. Their contemplation and prayer is particularly focused on the Eucharist, the wine and wafer, which, during transubstantiation, the wine and wafer become transformed into a representation of Christ's body and blood during the Mass.

Members of the active branch follow the Bible's teaching that when you care for the poor, you care for Jesus. They nurse the destitute through illness, teach the poor and street children, give shelter to the homeless and care "for the unwanted, the unloved and the lonely." That includes beggars, lepers and other people much of the world passes by.

The Sisters of St. Joseph follow their charism into a variety of social causes, working against the death penalty, racism, environmental damage and human trafficking.

Nuns and sisters have provided a large part of the labor force in many Catholic schools, hospitals and other institutions.

The Darker Side of Sisterhood

Not everything nuns do has enhanced the glory of God. They have also been part of some of the Catholic Church's many scandals, such as Ireland's Magdalen Laundries. From 1837 to 1992, for instance, the Sisters of Our Lady of Charity ran the Donnybrook Laundry as a workhouse and a home for "fallen" women, those who'd had sex outside of marriage. The discovery of a mass grave on the property for women who'd died while under the order's control touched off a major scandal.

The original vision for the Magdalen Laundries was to train fallen women so they could redeem themselves with a respectable career. Over time, the laundries became prisons, with women staying for years even though they'd committed no crimes. Even victims of rape and abuse were sometimes sent there. Nuns beat women for minor infractions of discipline or forced them to sleep outside in the cold or eat off the floor. The sisters shaved women's heads, forced them to wear institutional uniforms and put them on bread-and-water diets. There was little oversight and when inmates reported the abuse; few people were willing to believe such horrifying stories about nuns. Only when the media broke the story about the laundries' history, did people accept that the accounts were real.