The end documentation in the MLA system is called a Works Cited page. It is a list located at the end of a document or book and contains all the bibliographic information needed to find out more about cited source material.
This list is a selective bibliography and does not include a full accounting of sources related to or consulted before you began writing your document, but only those actually cited.
Proper MLA documentation depends on this list. Without it the in-text citations would make little sense as they would no longer be pointing to corresponding entries in the end documentation.