A person’s credit score is the aggregate of a number of different factors used in assessing your credit rating and used to judge how good a risk you are when it comes to giving you credit or a loan.
Your credit score is created and held by credit reference agencies and is used to help potential lenders decide whether or not you will be a reliable customer or not. Potential lenders use credit scores from a number of credit reference agencies along with data from other sources to create a profile of your previous credit history. Once they have all this information in place they are then able to determine whether or not to give you credit, your interest rates and your credit limit.
Because each lender has their own system of judging your final credit score there is no single method to fixing a poor credit rating, however, paying bills in full and on time, keeping within any existing credit limits and even registering on the electoral role will all help making you more credit worthy.