What is an idiom? The defining feature of an idiom is that you usually cannot understand its meaning from a literal translation of its words.  Why should I learn idioms?

• • Among native speakers of any language, the use of idioms is widespread. In fact, a language would be incomplete without them. You would have to be barking mad to suggest otherwise.
  • We use idioms all of the time – on the radio, on the TV, in the news, in magazines, at social gatherings or when we are just making small talk with a colleague at work.
• • They really are thick on the ground.
  • Unless you understand idioms and how to use them in the correct context, you cannot become fully proficient and sometimes you may even feel all at sea – unable to understand what is going on.