Firstly, it's the knowledge about language.

Secondly, it's the ability to use language.

Thirdly, it's a rule that helps us talk about language.

Fourthly,it's the attitude and mindset or the way of thinking about language.

We can use nonverbal communication and grammar without even thinking about it. We can usually "Do" grammar automatically because we have gained tons of knowledge about it since our childhood.

The reason why we should learn grammar is that we can communicate more accurately and efficiently. If our ability of grammar is weak, people around us might feel uncomfortable with it and take a lot of energy to understand us even worse, have a bias against us. If you know about grammar well, you can convey your thoughts clearly and other people trust you well.

Thanks for reading this ! ; )

The picture was taken in Shinjuku Station, where I had ramen with my friend last week.