Does Drupal keep timestamps of every time node is updated I'm wondering whether Drupal keep tracks (keep timestamps) of every time a node is updated (not just the last updated). If it does, how could I access this in the front end?
Yes, Drupal stores the updated date, but for that you need to enable revisions on  the content types you need it. From your revision table, you can get when a node has been modfied. You can also get how many times you have created a revision and other revision details.

Check the node_revision table; you will get the details.