Macros stands for macro-nutrients. We divide our macros into fats, protein, and carbohydrates. On keto, we get most of our calories from fat. On a standard American diet, we would normally get about 50% of our calories from carbohydrates. On keto we want to try to keep our carbs to only about 5% of our calories in a day. We also want fats to be about 75% of our calories in a day.
Keto vs. Atkins
A ketogenic diet is very similar to the Atkins diet. The difference is in the macros. On Atkins, you would keep your carbs low, but most of your calories would come from protein instead of fat. On keto, the high fat ratio is what puts our bodies into ketosis.