OPEX

OPEX covers the day-to-day costs of running a business that aren't directly tied to producing a specific product — salaries, rent, marketing, software, and admin.

OPEX sits below COGS on the P&L and is what's subtracted to move from gross profit toward operating profit. Marketing spend is almost always classified as OPEX, which is why a marketing team's budget decisions flow directly into operating margin, not just into a separate "marketing P&L" disconnected from company-wide profitability.