my cockatiel

Question
I have a cockatiel whose approximate age is 6 months. I have noticed that at the end of its feathers, it actually looks dirty? What could this be from?

Answer
Looks dirty and is dirty are two different things. Put a drop of water on the tip to see if it is dirt.They often have variegated feather tips that look dirty.
If it is dirt then the cage floor is too dirty. They do get on the floor of the cage from time to time.
Elevate the floor with wire or change the paper more often.