Nomad in the space of 0's and 1's

Very often you get this error on drupal and it happens more specifically after u have edited some file with php start and end tag.First of all this is a php error/warning message and has nothing to do with drupal but is often hard to debug in drupal coz of so many included files, this error is usually caused due to white spaces before the <?php tag ( you don't need a closing tag in drupal related code ). Sometimes your editor also adds a blank line after the closing tag and for that matter any whitespace will cause this error ..