What is TXN on card?

Excuse me, I'm a bit confused about something I saw on my financial statement. Could you please clarify what the abbreviation "TXN" stands for when it appears on a card transaction? I've been doing some online shopping recently and noticed this term popping up, and I'm not entirely sure what it represents. Is it related to a specific type of fee or charge? Or is it some kind of code used by the payment processor? I'd appreciate any insight you could provide to help me understand this better. Thank you in advance for your time and assistance.