Indexing is used for faster search or to retrieve data faster from various table. Indexes are created on columns in tables or views. The index provides a fast way to look up data based on the values within those columns.
You can create indexes on most columns in a table or a view except those columns configured with large object (LOB) data types, such as image, text, and varchar(max).
An index is made up of a set of pages (index nodes) that are organized in a B-tree structure. This structure is hierarchical in nature, with the root node at the top of the hierarchy and the leaf nodes at the bottom