The comprehensible input movement
Once upon a time, a linguist called Stephen Krashen came along and dropped a bombshell on the ELT world.
According to Krashen, learning languages is a complete waste of time. It involves remembering rules, repeating after the teacher, trying to memorise words, doing grammar tasks.
Krashen says that we acquire languages in one way, and one way only - through CCI: compelling, comprehensible input.
In short, we acquite language when we read or listen to messages that we understand, and even more so when those messages interest us.
Language production (speaking and writing), says Krashen, is a consequence of language acquisition. In short, this means that speaking and writing is just something that we do after we've acquired the language. It's not something that we do in order to acquire the language.