A banker's draft is a cheque drawn on the bank (or building society) itself against either a cash deposit or funds taken directly from your own bank account.
A banker's draft is thought of as being a secure way of receiving money from someone you don't know where you fear his/her cheques may bounce (not be honoured) and where it's not convenient or desirable to receive cash. Banker's drafts are commonly used for large purchases such as homes and cars; your bank or building society will generally charge a fee for issuing a banker's draft.