grammar is the sentences where it is formed correctly according to the rule of arranging sentences. grammar is one of skills in English where it is very difficult for some beginner especially who do not know parts of speech before it. 

many people study grammar and need long time because they haven't known the tricks. the tricks that may work for all students are by knowing "PANCAVIP". PANCAVIP stands for Pronoun, Adjective, Noun, Conjunction, Adverb, Verb, Interjection and the last is Preposition. from all parts of speech that is really important is " verb".

why must be verb that we have to know first in studying grammar? because in sentences especially English needs verb, either ordinary verb or auxiliary verb. we have to know which one is verb and which one is not verb. how to know that the sentence is verb?. all sentences in English consists of verb, but sometimes ordinary verb and sometimes auxiliary verb. we must know auxiliary verb, like to be ( is,am,are,was,were,be,been,being). if after those to be followed with adjective,noun and adverb it must be nominal sentence., primary (do,does,did.have.has,had) and modal (can,could,must,have to,had better, and so on). if you know them well, you will understand which one is verbal and nominal sentence.