Acquiring vocabulary is probably the essential thing foreign language learners should do. Not only because knowing a lot of words makes you sound smart but also because words and phrases are the building blocks of all languages.
As you’ve probably read in my “How to form sentences” article, we build sentences from words, and the more words you know, the easier the sentence-making process becomes.
However, we don’t only need vocabulary for making sentences; we also need a vocabulary to read. Fully understanding a text requires knowing at least 98% of all the words in the text (and this does include the non-content words like the, but, etc.), and you can only imagine how much time it takes to understand a text if you only know 70% or 50% of the words in a text.