Synchronization is how data moves between the mobile app and the website. As such, it is important to make sure that your data is synchronized before and after making any major changes.
You can check the sync status of the app at any time on the main menu, and start a manual sync at any time by clicking on the circle icon next to your login information.
You can also enable auto sync and prevent your device from synchronizing when it is not connected to wifi on the settings page.