Magento Local.xml for updating and Overriding XMl Structure

As Magento had important role of XML.while chnaging themes or Removing any block or layout chnages we are going in the each xml file of our theme and changing but there is one more solution that each time we don't need to update the each  xml

The idea behind is the local.xml, placed inside your theme layout folder to override or update all xml references for that theme.

Every change to the local.xml file is evident so there is no need to search for changes inside xml files