Why are weeds growing in my grass and how can I prevent them from taking over my lawn?

Weeds grow in your grass because they are opportunistic plants that thrive in areas where the grass is weak or sparse. To prevent them from taking over your lawn, you can maintain a healthy lawn by regularly mowing, watering, and fertilizing it. Additionally, you can manually remove weeds or use herbicides specifically designed to target weeds while sparing your grass.