index allows to search record in a table making the search 
meachnism faster and effective

index is a physical address of the data.Index having 2 
types.
1) cluster index
2)nonclustered index

INDEX are physical address of data, its is same just we 
Have indexes in our Book..through this we can make our 
search much faster.
in Idle way always try to make Indexes on that Column which 
have Integer Value(i.e. Not on text type).
There are two types of Indexes in SQL SEREVR
1. Clusterd Index.(Create automatically if there is a 
Primary key on Table)
2. Non Clusterd Index.

Index means we create unique id to record in to the table.

primary key is example of index; using proper index we 
search perticular record from database fast and accurate.

Index is a such type of mechanism in which records are
searched and fetched efficiently and fastly in a table. It
is physical address of data.

Two type of index : 
A. Cluster Index
B. Noncluster Index

An index is a physical structure containing pointer to the 
data.Index are created in an existing table to locate rows 
more efficiently and quickly.

Indexes in SQL Server are similar to the indexes in books. 
They help SQL Server retrieve
the data quickly.

There are clustered and nonclustered indexes. 
A clustered index is a special type of index
that reorders the way in which records in the table are 
physically stored. Therefore table
can have only one clustered index. The leaf nodes of a 
clustered index contain the data
pages.
A nonclustered index is a special type of index in which 
the logical order of the index
does not match the physical stored order of the rows on 
disk. The leaf node of a
nonclustered index does not consist of the data pages. 
Instead, the leaf nodes contain
index rows.