Gross Profit
Gross Profit is the amount of dollars remaining after Revenue has been reduced by Cost of Goods Sold (COGS).
Investors care a lot about Gross Margin & COGS because they can’t be modified. So, if you have 50% Gross Margin (Revenue - COGS), then the other 50% of the business you can theoretically work with. It’s much more difficult to decrease COGS than OpEx.
In the room
Gross margin is the first thing a banker looks at when sizing up a business, because it's the hardest number to change. Being able to say why a buyer cares more about gross margin than operating margin shows you can think like an investor. You can cut overhead, you can't easily cut the cost of making the product.