The common phrase 'idioms and phrases' refers to commonly used groups of words in English. Idioms are used in informal situations, whereas phrases may also be rather formal. Learning idioms and phrases is an important part of learning English as it's common to string phrases together rather than individual words. These idioms and phrases are used in specific situations and often used in an idiomatic, rather than a figurative sense. Idioms are often full sentences. Phrases, however, are usually made up of a few words and are used as a grammatical unit in a sentence. Here are some examples of common idioms and phrases.
It's raining cats and dogs (idiom)
at the top of (prepositional phrase)
chairman of the board (noun phrase)
by the end of the day (adverbial phrase)
Pronunciation: ˈɪdiəm ænd freɪz