Syncing means importing all files, permissions and data's from master to the development site, so that we have a two copies of live sites to test our new developments. In Drupal, its very easy to create versions of websites using this syncing process. Once the site is live to Production, the above process helps to fetch the sites data in the current scenario and to update few more features in the live site.
I had a task to sync live database to development site's and came across some issues while syncing live database with the dev database.