Whether you’re applying for a mortgage, taking out a loan or signing up for a new credit card, one number carries more weight than many people realize: your credit score.

In this week’s personal finance edition of Merryn Talks Money, hosts Merryn Somerset Webb and John Stepek are joined by John Webb, senior consumer affairs manager at Experian and an expert on credit scores. Together they explore the world of credit scores—what they are, how they’re calculated, why they vary across agencies and the many ways they can shape your financial future.