Why is that junk(start.aspx#/../) getting added in sharepoint 2013 url?
Why do the urls in sharepoint 2013 do not look like they were anymore?
Untill 2010 Sharepoint used to reload the entire page for every request sent from browser. In 2013, a site scope featured, Minimal Download Strategy(MDS) is introduced that will minimize the content to be downloaded from server when user navigates from page to page.
When request is sent from browser, the delta is calculated which is equal to the difference between the current page content and the response for the new request. This delta will be sent to MDS engine and start.aspx is responsible for loading the changed content in the page.Anything after start.aspx# represents the relative url of the target page. Page is completely reloaded only when MDS thinks its not just part of the page that changed but all of it and for other reasons listed here. This feature is optional and considered to improve any performance on the page. Be aware of this feature activation status when writing any client scripts playing with url or trying to do something on document ready, because page may not be reloading so do your scripts.