Okay im still confused at this. So the backup file on my electrum is the 12 word phrase... theres nothing else.
But for my blockchain, what is my backup file? I downloaded it and sent it to my email and its 2kb. Is it also the 12 word phrase or its something else? I couldn't open it because it said you need some program to open it.
You need both for blockchain.info. The mnemonic, which is actually a different version of your password, and the wallet file which contains your encrypted private keys. Over time you need to create fresh backups of your wallet file and if you change you password you need to copy over the new mnemonic as well.
In electrum all the private keys are derived from the seed which is represented as a 12 word mnemonic. Those 12 words are all you need to backup. Of course you should still set a password for the wallet file on your computer so that in case somebody or some program gets access to the wallet file they can't spend your bitcoins because the seed is encrypted with a password.
If I were to simplify this:
blockchain.info backups:
- latest wallet file (aes.json) + mnemonic
Or
- latest wallet file (aes.json) + password
Regular backups required
electrum backups:
- seed only
Or
- wallet file + password
One time backup suffices.