The sysindexes table lists each table and index and the segment where each table, clustered index, nonclustered index, and chain of text pages is stored. It also lists other information such as the max_rows_per_page setting for the table or index.
The create table, create index, and alter table commands create new rows in sysindexes. Partitioning a table changes the function of sysindexes entries for the table, as described in Performance and Tuning: Basics.