Normalization of a database helps in modifying the design at later times and helps in being prepared if a change is required in the database design.
1nd Normal Form or 1NF:
Each Column Type is Unique.
2nd Normal Form or 2NF:
1NF + all attributes within the entity should depend solely on the entity’s unique identifier.
3rd Normal Form or 3NF:
2NF + no column entry should be dependent on any other entry (value) other than the key for the table. If such an entity exists, move it outside into a new table.
A slightly detailed article (PDF) covers Lossless Join etc.
2. Problems without normalization – namely insertion anamoly, update anamoly and deletion anamoly
6. DBMS stores data internally in form of btrees
B-Trees are used to store the data on external storage like disks. Unlike main memory, disk access are expensive. So B-Trees tries to minimize the access