A database index is a data structure that improves the speed of operations in a table. Indices can be created using one or more columns, providing the basis for both rapid random lookups and efficient ordering of access to records. The disk space required to store the index is typically less than the storage of the table (since indices usually contain only the key-fields according to which the table is to be arranged, and excludes all the other details in the table), yielding the possibility to store indices into memory from tables that would not fit into it. In a relational databasean index is a copy of part of a table. Some databases extend the power of indexing by allowing indices to be created on functions or expressions. For example, an index could be created on upper(last_name), which would only store the uppercase versions of the last_name field in the index. Another option sometimes supported is the use of "filtered" indices, where index entries are created only for those records that satisfy some conditional expression. A further aspect of flexibility is to permit indexing on user-defined functions, as well as expressions formed from an assortment of built-in functions.

Runtime exceptions represent problems that are detected by the runtime system. This includes arithmetic exceptions (such as when dividing by zero), pointer exceptions (such as trying to access an object through a null reference), and indexing exceptions (such as attempting to access an array element through an index that is too large or too small).
Runtime exceptions can occur anywhere in a program and in a typical program can be very numerous. Typically, the cost of checking for runtime exceptions exceeds the benefit of catching or specifying them. Thus the compiler does not require that you catch or specify runtime exceptions, although you can.

Report Service manager in built Reporting Feature Available in 2005.
Major change is the integration of sql server 2005 with the .NET framework.
online indexing only in sql 2005.
CLR Integration with sql server 2005.
xml datatype in sql 2005.
More faster than sql 2000.

Fill factor is a defiened percentage between 0 to 100 in which we leave exra gaps to accomodate future
expansions in the storage of the futures data.
Indexing in sql is same as the index in our books. it helps us to manage our data more appropriately.it can be
done in two ways namely clustered index and non-clusterd index.we can create only one clustered index per table and maximum of 249 non-clustered indexes per table.

Optimization techniques are -
1.litmit
2.keys
3. indexing