You live once. Take charge of your English vocabulary.
No one knows every English word. That includes you. And that's fine. But, there are also many important, frequently used words, that you don't know. And that's not fine.
There are two key problems here. Firstly, you don't know which important words you don't know. Secondly, it's hard to learn them, and not forget anyway. But worry no more, as the right technology is finally here to help.