We don't study grammar of our own mother tongue to use it for daily speaking, but when we need to polish our own mother tongue, we have to study its grammar and we usually do that. When we come to learning a new language like English language, we need to study its grammar, the importance of grammar cannot be neglected and before we do that we need to understand what grammar is.
Grammar is the study of words and the ways words work together. An invisible force that guides us as we put words together into sentences. Any person who communicates using a particular language is consciously or unconsciously aware of the grammar of that language.
To speak in a clearer and more effective manner we study grammar. A person who has unconscious knowledge of grammar may be sufficient for simple language use, but the ones who wish to communicate in an artful manner and well, will seek greater depth of understanding and proficiency that the study of grammar provides.
Why is important to know English grammar and phonetics?
Whereas syntax is about sentence formation, and semantics about sentence interpretation, phonetics and phonology cover the field of sentence utterance.
Phonetics is concerned with how sounds are produced, transmitted and perceived. Phonology is concerned with how sounds function in relation to each other in a language.
As phonetics and phonology both deal with sounds, and as English spelling and English pronunciation are two very different things, it is important that keep in mind that they are not interested in letters, but in sounds.
For instance, English has not 5 or 6 but 20 different