There are two different aspects to index management. The first aspect is the management of indexes by the SQL Server Database Engine. Fortunately, the engine does a good job of managing the indexes internally so that limited manual intervention is required. This is predicated on a well-designed database system and the use of SQL Server features, such as automatic updates to distribution statistics.
The other aspect of index management typically comes into play when performance issues arise. Index adjustments and maintenance of these indexes make up the bulk of this effort.