A bitcoin wallet is a combination of a public address and a private key.
There are different types of bitcoin wallets;
Hot wallets – connected to the internet
Mobile wallet – installed in your phone
Cold storage wallet – Like a paper wallet
The idea is that the owner of the bitcoins memorizes the private key without writing it anywhere. For anyone to access your bitcoins, he or she has to acquire your private key.
Private keys are long strings of letters and numbers that are difficult to memorize, which makes bitcoin wallets to be unfriendly to users.
Nevertheless, you can generate your private keys by using a passphrase.
A paraphrase is a sequence of words, a sentence or other texts, eight words or more that can mathematically be converted into a private key.
For security purposes, a paraphrase should be an entirely original sentence, though must not necessarily have a meaning at face value. To generate a secure brain wallet passphrase, you can include some critical personal information, which is not necessarily a secret, like an email address or a phone number. A good passphrase will have dozens of characters. Here is an example of such a passphrase:
Your mother’s birthday multiplied by your favourite number, any word that holds a special meaning, your family home phone number when you were a kid, the first five words of your favourite English paper.
Using extremist characters or symbols such as #? &* make the passphrase hard to figure out.
Once you have memorized your passphrase, you can use programs such as brainwallet.org to generate your private key and public address from it. However, you must ensure your computer is offline, and you are using private browsing prevent someone from stealing your private key.
While brain wallet is a safe, secure and trustworthy option, it requires you to memorize the private key which is extremely difficult. And in any case, you lose your private key you also lose your bitcoins.