Straight from Castle Age!
New Feature: Daily Bonus
You may have noticed a new box on your home page. These are extra bonuses for players that are different every day. However, each day's specific bonus will remain the same for extended periods of time.
For example: Thursday's bonus is 2X Iron Collect. This will remain the same bonus on Thursday going forward for the foreseeable future. However, these are subject to change at a later date.
Enjoy and have fun!