An index is an object in the database which contains one or more columns from a single table. The data within the index is sorted which makes it much faster to search than searching the table it self.
There are a couple of blog posts which I’ve made about indexes.
<a href=”http://itknowledgeexchange.techtarget.com/sql-server/back-to-basics-whats-the-difference-between-a-scan-and-a-seek/”>What’s the difference between a Scan and a Seek?</a>
<a href=”http://itknowledgeexchange.techtarget.com/sql-server/back-to-basics-creating-indexes/”>Back To Basics: Creating Indexes</a>