MANI - I have never heard of a church excomunicating(if thats the word) members before. Why does the lds church do this? What are the top 10 causes lds members get kicked out of the mormon church?

JOEL - There are many religions that impose some form of formal discipline against members. The LDS Church applies disciplinary action to church members for three reasons:

(1) to save the souls of transgressors,
(2) to protect the innocent,
(3) to safeguard the purity, integrity, and good name of the Church.

These purposes are accomplished through private counsel and caution, informal probation, formal probation, disfellowshipment, and excommunication.
If a member should commit a serious sin that affects the health and safety of others such as murder, sexual asault, etc., society would expect the church to take some form of action to make sure that innocent people are helped or protected. It also sends a message to the community that such behavior is not condoned by the church.
The disciplinary process can help the member overcome the sin and help him repent and receive forgiveness for it.
There are really only a few reasons why a person would be excommunicated from the Church. Most sins are handled by counsel, probation, or disfellowshipment, all of which allows the member to maintain their membership in the church, but with some restrictions.
The only reasons for excommunication would be for serious sins such as murder, adultery, incest, child abuse, and open apostasy against the Church. The decision for excommunication for these sins depends on the circumstances and the member's current standing in the church.
Even if one is excommunicated it is possible for them to be readmitted into the church after proper repentence and some time has passed.