There is an infinitive way of learning a language. Screen your options before making a decision on how to start learning.
Sarcasm is used to express true meanings through opposite words and phrases. However, differently from irony, which simply is used to say one thing with the word of the opposite meaning, sarcasm can be deceitful and much more twisted.
Irony is a big part of cultural concepts in the English language. Learn what irony is, how and when it is used, and find useful examples.