If you run a service where you need to pay bitcoins out to users then that means your systems have to respond to user input and send money to them.
It turns out this is pretty tricky to secure.
The current popular strategy is to have hot and cold wallets. A hot wallet is online and can make payouts automatically.
A cold wallet is kept offline (airgap) and brought online by a human being to refill the hot wallet when it is running low. This only really makes sense if your service needs to secure large amounts of bitcoin for a long time without using them.
This recent bitcoinica hack is pretty inexplicable, they were keeping a large amount of coin in an account at an exchange called MtGox. This is effectively a hot wallet.
It turns out this is pretty tricky to secure.
The current popular strategy is to have hot and cold wallets. A hot wallet is online and can make payouts automatically.
A cold wallet is kept offline (airgap) and brought online by a human being to refill the hot wallet when it is running low. This only really makes sense if your service needs to secure large amounts of bitcoin for a long time without using them.
This recent bitcoinica hack is pretty inexplicable, they were keeping a large amount of coin in an account at an exchange called MtGox. This is effectively a hot wallet.