I am learning about indexes. I know that index forms a b-tree structure. But - what if there are no index on the table? What structure is this? If we add - let's say clustered index - is b-tree structure added to the table structure? If we delete the index is then whole b-tree deleted and only table structure remains? Everybody is talking about index structures, but one thing it's not clear to me - if everything in sql server is stored in pages - is table without index stored in pages, too? So, when we add index this new index is also stored in pages? How are both structures connected, or how both structures differ?