When running top or another system activity monitor on your Mac with OS X, you may notice a process called mdimport which is taking up a lot of resources. What does it do?

mdimport is a crucial process for Spotlight, the OS X file indexing engine. It is short for "metadata datastore import", and whenever you create or copy new files to your Mac, this process kicks off. It imports file data into a database so that Spotlight can find the correct file when you perform a search.

From a Terminal command line, run "man mdimport" and all of the ways you can run mdimport will be displayed. 

When you see mdimport, you are also likely to see LAServer running as well.