The word Scientology literally means "the study of truth". It comes from the Latin word "scio" meaning "knowing in the fullest sense of the word", and the Greek word "logos" meaning study of". Scientology is the study and handling of the spirit in relationship to itself, others, and all of life.
I have been a Scientologist since 1985, but was not as involved in the beginning as I am now. Scientology is an applied religious philosophy that can be used in all aspects of life. I have studied the philosophy and the related technology thoroughly. I have visited or been in contact with all the organisations of the Church of Scientology, so I can be regarded as a fairly skilled and knowledgeable Scientologist.
Of all philosophies, religions or lifestyles I have studied or been in contact with, nothing has given me a more embracive understanding of life in general than Scientology. This has of cause been a gradual evolvement, but has brought me to a point where I, despite a critical viewpoint, can vouch for the whole of the philosophy and all its practical applications.
The amount of material in Scientology is extensive, and it would therefore be a difficult task to describe, in a few sentences, what Scientology is and what it has meant to me. And even if I could then there probably isn't any other method, for the person who really wants to know, than to study the materials himself. This is easily done by reading a book, but there are also plenty of oppertunities to know more by studying about Scientology on the Internet.
On http://www.scientology.org/ you'll find much information about the activities of the church.
On http://www.whatisscientology.org/ you'll find further information about the religion.
On http://www.bonafidescientology.org/ you'll find a more theoretical approach to the subject.