Proper maintenance and tuning of indexes is a critical part of a database administrator's job. This whitepaper explores the differences between heaps and clustered tables, and between clustered indexes and nonclustered indexes. In addition to properly designing indexes in the first place, monitoring their use over time can help with eliminating unneeded indexes and adding new beneficial nonclustered indexes. As the data is updated, the efficiency of indexes can decrease because of fragmentation. Periodic index maintenance eliminates or reduces fragmentation so that performance of applications and reports does not decrease over time, which is also discussed in this whitepaper.