396 Baptism

On Tuesday, neyyo and I were discussing baptism. During that discussion, it became clear to me, that a deeper dive into this subject might be needed.
What does the word “baptism” mean?
How many types of baptism are found in scripture?
What is the Old Testament predicate for baptism?
Is baptism only for the believer or the whole family of the believer?
Is baptism needed for salvation?
Does baptism require that a person be submerged in water?