IDIOM

English Idioms
An idiom is a set expression which has a meaning different from the literal meanings of its components. Idioms present a great variety of structures and combinations that are mostly unchangeable and often not logical and may not follow basic rules of grammar.
Idioms can be quite clear (in general; come out; at first; the root of all evil) or pretty unclear (on end; pack it in; high and low; hard cash). Some idioms have proper names in them (a Jack of all trades; Uncle Sam); some other idioms are comparisons (as clear as a bell; as the crow flies). Proverbs and sayings may also have idiomatic character (every cloud has a silver lining; still waters run deep).
It is pointless to ask why idioms have such unusual structure or choice of words, or why they don't follow basic grammar rules. Let's just accept as fact that idioms are a difficult peculiarity of English.
In the section Idioms, we are going to study useful idioms that native speakers use frequently in their everyday life. These idioms are accepted as part of everyday speech and undoubtedly are of great practical value to you. Many other idioms, though they are often interesting and colorful, are not so necessary in your everyday conversational English. Short lists of everyday idioms in this section include the most common idioms that you need to learn by heart and use actively in your speech.