How to Use Grammar?

Grammar is simply the way we combine words together so that other people can understand us.

For example: 

• The sentence "The pretty is dress" is difficult to understand. 
• The sentence "The dress is pretty" is clear.

• The sentence "She is ate lunch" is difficult to understand. 
• The sentence "She is eating lunch" is clear.

• The sentence "John is the more old Lisa" is difficult to understand. 
• The sentence "John is older than Lisa" is clear.

So clear communication (expressing ideas and giving information) is the real purpose of grammar, and we shouldn't forget that.

There are many rules, but what's the ultimate goal? 

The ultimate goal is understanding other people and being understood by them.

By knowing grammar very well you can get across exactly what you want to say.