An idiom is a form of expression peculiar to a language. It is a phrase or an expression whose meaning cannot be understood from the ordinary meanings of the words in it. “How do you do?” “He was assassinated in cold blood” are English Idioms.
An appropriate use of idioms and expressions introduces a variety in writing English and gives it a zing. To ask about the meanings of idioms and expressions is to ask about everything. To use them with skill and integrity is to become a master of expression. The application English Idioms contains some important idioms and expressions in everyday use with their meanings and examples. Use them in your writing, whenever you think it fit to do so.