Standard  usage includes those words and expressions  understood, used,  and accepted by a majority of the speakers of a language in any situation regardless of the level of formality. As such, these words and expressions are well defined and listed in standard dictionaries. Colloquialisms, on the other hand, are familiar words and idioms that are understood by almost all speakers of a language and used in informal speech or writing, but not considered appropriate for more formal situations. Almost all idiomatic expressions are colloquial language. Slang, however, refers to words and expressions understood by a large number of speakers but not accepted as good, formal usage  by  the  majority.  Colloquial  expressions  and  even  slang  may  be  found  in standard dictionaries but will  be so identified. Both colloquial usage and  slang are  more common in speech than in writing.

Colloquial speech often  passes into standard speech.  Some slang  also passes into standard speech, but other slang expressions enjoy momentary popularity followed by obscurity. In some cases, the majority never accepts  certain slang  phrases but  nevertheless retains them in  their collective memories. Every generation seems to require its own set of words to describe familiar objects and events.

It has been pointed out by a number of linguists that three cultural conditions are necessary for the creation of a large body of slang expressions. First, the introduction and acceptance of new objects  and  situations  in  the  society;  second,  a  diverse  population  with  a  large  number  of subgroups; third, association among the subgroups and the majority population

Finally, it is  worth noting  that the terms "standard" "colloquial" and "slang" exist only as abstract labels for scholars who study language. Only a tiny number of the speakers of any language will be  aware that they are using colloquial or slang expressions.  Most speakers  of English will, during appropriate situations, select and use all three types of expressions.全文翻译：

语言的类型  标准用法包括那些为使用这种语言的大多数人在任何场合下理解、使用和 接受的词和短语，而不论该场合是否正式。

这些词和短语的意义已很确定并被列入了标准 词典中。相反，俗语是指那些几乎所有讲这种语言的人都理解并在非正式的口头或书面中 使用，却不适用于更正规的一些场合的词和短语。  几乎所有的习惯用语都属于俗语，而俚 语指的是为很多讲这种语言的人理解但大多数人不把它们列入好的、正式用法之内的词和短 语；俗语甚至俚语都可能在标准字典中查到，但是字典中会标明它们的性质。

俗语和俚语 词汇的应用都是口头较多、笔头较少。俗语用法经常地被接受为标准用法。  一些俚语也变 成了标准用法，但另外一些俚语只经历了短暂的流行，而后就被弃之不用了。  有时候，多 数人从来不接受某些俚语，但是他们把这些俚语保存到集中记忆中。

每一代人似乎都需要 独有的一套词汇来描述熟知的物体和事件。  很多语言学家指出，大量俚语的形成需要三个文化条件：第一，对社会中新事物的引入和接受；第二，一个由大量子群构成的多样化人口； 第三，各子群与多数人口之间的联系。最后需要提到的是，"标准语"、"俗语"和"俚语"这些 术语只是对研究语言的专家才有用的抽象标签。

不论何种语言，只会有很小一部分使用者能够意识到他们是在使用俗语或俚语。  讲英语的多数人能够在适当的场合中选择使用所有 这三种语言类型。