There are some universal truths about human language whose understanding can greatly facilitate the learning of a second language. There are also important grammatical principles that make the English language similar, but different from other spoken languages.
Without a solid understanding of the vocabulary of grammar it is nearly impossible to discuss the rules of any language. With a good understanding you can ask intelligent questions, perform effective internet searches, and utilize well-organized on- and offline reference materials to solve your own problems. With the vocabulary of grammar dictionaries and grammar books begin to make sense.
This is where you come to learn the rules of the English language: how to assemble the words of the language in meaningful messages that others can understand on the one hand, and how to separate the sense from the nonsense of your own and other people's messages.
How we order these words and phrases is determined by the rules of grammar and the logic of our own message.
At the end of each word or phrase is a set of limited options from which we must choose. Upon the completion of each new phrase there are a different set of options. The better we understand these options and how to select from among them, the better we are able to express ourselves in a clear and precise manner that others can easily understand.
The more complex or more poorly ordered our message becomes, the more difficult it is for others to understand.
Dividing our messages into their logical parts not only insures that we understand each other's messages, but also what is missing or not yet understood.
Learning how to ask the proper questions is an important skill that insures proper understanding.
Then too, a lot of people speak and write nonsense. Learning to ask the proper questions helps us to separate the sense of what we say and write from the nonsense of what is heard, uttered, read, and written.
Grammar Captive claims to know a lot, but it does not claim to know everything. If a reference that you know is missing, provide it, tell Grammar Captive what makes it special, and Grammar Captive will post it for you with a note of thanks.