In short: credit is an agreement under which you receive money or goods now and promise to pay later, usually with interest and fees — a price you pay today for money from tomorrow.
Simply put: three words are at its heart: principal (how much you get), interest (the price of the money) and term (by when you repay). Credit is offered by banks, non-bank lenders and sellers offering instalments. What matters is not only "how much does it cost" but also "how will I pay it back".
Example: you borrow €1,000 for one year at 10 % annual interest and repay it all at the end — €1,100. The €100 is the price of the credit.
Watch out: not everyone who lends money is a bank. Check who the lender is and who supervises it.
The EU rule: under Directive 2008/48/EC (Article 3(b)), a creditor is anyone who grants credit in the course of their trade, business or profession; banks are licensed, while other lenders are regulated under national law.
Example: Bulgaria — banks are licensed by the Bulgarian National Bank (BNB); non-bank financial institutions are not licensed but entered in a public BNB register (Credit Institutions Act, Article 3a). Entry is not an assessment of the product.
Check in your country — Which authority keeps the register of lenders? Search it for the company's name before you sign.
Source: Directive 2008/48/EC — https://eur-lex.europa.eu/eli/dir/2008/48/oj; BNB register of financial institutions: https://www.bnb.bg/RegistersAndServices/RSFIRegister/index.htm