It might be because you either have not payed for minecraft with your account, or have payed for it, but deleted your .minecraft folder and tried to log in without username or password. If not either of these reasons, try resetting your computer.
The Minecraft login servers may be down for a period of time.
Because minecraft has the best graphics ever and you need to a million dollar graphics card. And also it's insane graphics would chew up your internet allowane at 50GB per second
It's just buggy these days. It just doesn't work.
You can try to delete Minecraft.exe, and re-download it from the website.
NOTCH
Minecraftnet is the only place where you can register the premium account that you need to play the full version of Minecraft.
Yes!
Because It has to many people on it
Maybe there are construction for updates on their website, or bad Internet
There is no other LEGAL place to buy Minecraft.
If you own Minecraft on that account then YES!
Because they are upgrading their website, it says that for everyone.
you right click to put the saddle on the pig then you right click the saddle while it is on the pig.
minecraft.net might be offline.
As of July 2013, the website Minecraft.net does not have a polka dot mod available for its users. This may be implemented by the website in the future, however.