Baptism is an outward symbol of one's commitment to Jesus. People are not saved by being baptized. By being baptized, is an act of obedience to God when one accepts Jesus as their Lord and Savior. Baptizing people in the name of the father, son, and Holy Ghost is part of the Great Commission.
And Jesus came and said to them, "All authority in heaven and on earth has been given to me. Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you. And behold, I am with you always, to the end of the age." ~ Matthew 28:18-20 (ESV)
I go to a Baptist church where we fully submerge during baptism which symbolizes the death to the old self and rebirth into a new life in Jesus.
Then Jesus came from Galilee to the Jordan to John, to be baptized by him. John would have prevented him, saying, "I need to be baptized by you, and do you come to me?" But Jesus answered him, "Let it be so now, for thus it is fitting for us to fulfill all righteousness." Then he consented. And when Jesus was baptized, immediately he went up from the water, and behold, the heavens were opened to him, and he saw the Spirit of God descending like a dove and coming to rest on him; and behold, a voice from heaven said, "This is my beloved Son, with whom I am well pleased." ~ Matthew 3:13-17 (ESV)