In the Catholic faith what is excommunication?

Excommunication kicks you out of the Catholic Church. It does not condemn you to hell.

Using bigger words:

Excommunication is a severe penalty resulting from grave crimes against the Catholic religion.

It is imposed by church authority or incurred as a direct result of the commission of an offense.

Excommunication excludes the offender from taking part in the Eucharist or other sacraments and from the exercise of any ecclesiastical office, ministry, or function.

The option of admitting your error and returning to the Church is always open.

With love in Christ.

excommunication

Form of censure by which a member of a religious body is excluded from the congregation of believers and from the rites of the church. Excommunication has been used in various religions, notably Christianity, as a punishment for grave offenses such as heresy. In Roman Catholicism an excommunicated person is barred from receiving the sacraments and from burial in consecrated ground. The offender may be absolved by a priest (in some cases, only by a bishop or the pope) and received back into the church after confessing his or her sin and doing penance for it. In Protestant denominations other terms, such as “church discipline,” may be attached to essentially the same censure. Although now seldom used, the practice of herem in Judaism was a form of excommunication that excluded people from the community for prescribed times or forbade them from hearing the Torah. The term is also applied to the expulsion of Buddhist monks from the sangha.

Pretty much, you're thrown out of church and your faith reject you. It's only for those who have done something really wrong that is beyond any human forgiveness. In the old days, heterics were excommunicated for talking against the church. We're a lot more forgiving now.

1463 Certain particularly grave sins incur excommunication, the most severe ecclesiastical penalty, which impedes the reception of the sacraments and the exercise of certain ecclesiastical acts, and for which absolution consequently cannot be granted, according to canon law, except by the Pope, the bishop of the place or priests authorized by them. In danger of death any priest, even if deprived of faculties for hearing confessions, can absolve from every sin and excommunication.

It happens in extreme cases when a proclaimed member of the Catholic Church, Preaches heresy. (Mis-Representing or lying about the Faith) Openly.

It is the only way to show that radical teachings are NOT from the Church.

You might ask here:

www.Catholic.com

Excommunication mean you are severed from the body of the church. It is a latin break down basically meaning we will not talk to you anymore in this church.

When someone commits a grave sin against the church and does not ask for or cannot be given absolution. Or they do not believe that what the Church says is true.

Cuttign off of a person from fellowship in the church. Not sure how it works in Catholicism, but in my church, it means that they are cut off until they repent of their sin. You can still be friends with that person and should continue to pray for them, but if he calls and invites you out for a beer, you need to tell him "I'd love to, but first we need to talk about your issue". The idea is not so much to punish someone, but to reconcile them to God and provide means for the introspection that, hopefully, will lead that person to return.

It means you are no longer a part of their church and faith. you have done something profane in their eyes that is not acceptable and they turn you away.

Kicking you permanently out of church for some imagined heresy as defined by holey mudda church.