Hello bitcoin sages,
Could you please tell me: Is there a way to store bitcoin on a laptop/ usb drive / mobile without needing a lot of HDD / SD card space ?
I need a wallet / solution file that would not take up space, yet be accessible at (a fairly) short notice
Much love
Then you should avoid BitcoinQT (core wallet) and try MultiBit (multibit.org). It takes only a few seconds to sync and use.
Why ? Does BitcoinQT require to DL the blockchain ?
Yes, BitcoinQT downloads the whole blockchain data, which is usually several GB.
MultiBit is a 'lite' client which downloads most recent block info, but is equally good & secure for most users.
Incorrect, Multibit is a SPV client which downloads the header of every block. SPV clients trust miners to enforce the network rules, full-chain client does not trust miner this way. Bitcoin Core is currently near 27 GB, headers-first synchronization should cut down the initial sync time in the next stable release (v0.10).