Children are often baptized, but only after they know for sure Jesus is their Savior and that they are trusting Him for eternal life. There is no special age when they should be baptized, as long as they understand what it means. Many important things happen in the courts of heaven and on the books of eternity when you receive Christ into your life. Water baptism symbolizes some of them in a physical way. It reminds you and tells other that you're starting a new life.
Baptism symbolizes a bath-a thorough cleansing.
Jesus made that possible. The water is the symbol of the clean conscience and heart God gives you when you take His grace. And baptism is Christ's visual aid of the cleansing already accomplished in the life of a Christian. Baptism symbolizes the Holy Spirit's work of placing you in Christ. Baptism is a mysterious, beautiful action God sees and you understand only as you believe Him.