When we say something is common, it’s like when you and your friends all have the same favorite toy. If everyone in your class has a toy car, then toy cars are common in your class. It means that many people have or know about it.
Think about a sunny day. Sunny days are common in the summer because they happen a lot. You see the sun shining almost every day, so it’s not a surprise. It’s like a routine that everyone expects.
Imagine a big box of crayons. If there are lots of red crayons, then red is a common color in the box. It means there are more of them than the other colors. It’s something you see a lot, and it feels normal to have them around.
When you go to the park and see many trees, trees are common there. It means they are everywhere, and it’s usual to see them. It’s like when you have lots of apples in a basket, apples are common in that basket.