How a credit bureau decides whether you're creditworthy.
Credit bureaus collect data on accounts, loans, contracts and missed payments and condense it into a probability that you'll pay on time. Positive signals: long-standing accounts, punctual instalments, few credit enquiries. Negative signals: collection proceedings, many new loans, unusually many current accounts and credit cards. In the EU, the GDPR gives you the right to see what's stored for free.
Useful: Request your own report once a year and get incorrect entries fixed.
Source: en.wikipedia.org