A bad credit profile will occur if you do not repay money borrowed in line with your credit agreements or have had legal proceedings against you.
This could mean a history of:
Late or missed payments
Unpaid debts
Repossession of home or assets
Filing for bankruptcy
County Court Judgements (CCJs) and Individual Voluntary Arrangements (IVAs)
Credit scoring differs between agencies and lenders, but you can access your credit report online from a credit reference agency like Experian or via an app like ClearScore.