Let's assume that we have a drupal website and we have search (Search API) option on it. We will do search and drupal will get the search result from index. Now we had a special requirement, i.e we need to exclude a page from search result not a entire content type. This means we need to exclude a page from being searched.
To achieve this we found a module Search Exclude nid, this is usefull if you have very limited no of node to exclude.