Calorie counting means logging everything you eat and drink along with its energy content, usually in an app or a food diary. That way you know how much you take in per day on average and can steer a surplus or deficit on purpose.
A tool, not a must
Calorie counting is a tool. Some people work with fixed portions and only watch their trend. What matters is that you notice when your trend weight drifts from your goal and then adjust. Counting has one big advantage, though: from your intake and your trend, you can calculate your own maintenance instead of just estimating it.
Consistent beats precise
It is well documented that people misjudge their intake. In a study by Lichtman and colleagues (1992), participants with obesity who did not lose weight despite dieting reported eating 47 percent less on average than they actually ate. With a kitchen scale you will usually be much closer.
A consistent error does not make the method useless. If you always log about 10 percent too little, your calculated maintenance will be too low by the same amount, but it is calculated in your own currency. As long as you keep logging the same way, your target calories still end up where your trend wants them.
The most common mistakes
The biggest mistake is gaps. If the days with a restaurant meal or birthday cake are missing, your average is too low. Log roughly rather than not at all.
Example: An estimated entry like "pizza, about 1,100 kcal" is far more useful for calculating your maintenance than an empty day. The number is an example.
Just as important: hit your targets on a weekly average, not to the gram every day.