Ramadan Kareem

Ramadan Kareem! - phrase used by Muslims which literally means "Have a generous Ramadan". 

When this crescent moon is sighted on the last day
 of Shaban it means Ramadan officially begins

It's the Holy month of Ramadan where I'm currently based at. Basically, Ramadan observance follows Shaban, the eight month of the Islamic calendar. Unlike, says, January, Ramadan and Shaban do not have the fixed number of days. Each month can have 29 or 30 days depending on when the first silver of the crescent moon is sighted by the naked eye. If, on the 29th day of Shaban, the crescent moon is sighted, Ramadan has begun and Muslims begin fasting on that morning. If the moon isn't sighted that night, Shaban last 30 days. And Ramadan will begin the next day whether the moon is sighted or not.