Normalization a procedure used to eliminate redundancy and functional dependencies between columns in a table.
There exist several normal forms, generally indicated by a number. A higher number means fewer redundancies and dependencies. Any SQL table is in 1NF (first normal form, pretty much by definition) Normalizing means changing the schema (often partitioning the tables) in a reversible way, giving a model which is functionally identical, except with less redundancy and dependencies.
Redundancy and dependency of data is undesirable because it can lead to inconsisencies when modifying the data.
