How to Use Gerunds in English - Basic English Grammar

In this video, Alisha answers 5 questions. - Could you please explain gerunds to us? - I sometimes hear people say (better) instead of (improve), as if it is a verb. Is that formal? For example: Think about how to better yourself. Also, I heard someone say "more better," and it sounded strange to me. I mean, can I say "he is more taller than me?" - Could you tell me the difference between correct and right? - Why don't native speakers use specific times in present perfect but they do use specific times in simple past tense? - A lot of people use double negation lately. Is it a kind of innovation? Can we use it? Is it grammatically correct?