To make up for downtime

Blizzard is giving players on many realms 48 hours of time back to make up for the recent 48 hours of down time.

Blizzard is compensating players who experienced downtime on select realms...
To compensate players for any inconvenience caused by the downtime experienced as a result of this week's 48 hour extended maintenance, we will be issuing a 48-hour time extension to all players who have accounts that are currently active on the following realms.

Click read more if the complete list does not appear.