自动标引（英语：Automatic Indexing）包括关键词自动提取（又称自动抽词标引）与自动赋词标引两种类型。关键词自动提取是一种识别有意义且具有代表性片段或词汇的自动化技术。关键词自动提取在文本挖掘域被称为关键词抽取（英语：Keyword Extraction），在计算语言学领域通常着眼于术语自动识别（英语：Automatic Term Recognition），在信息检索领域，就是指自动标引。自动标引属于文本信息抽取的范畴。文本信息抽取是从文本数据中抽取人们关注的特定的信息。

Automatic indexing is the ability for a computer to scan large volumes of documents against a controlled vocabulary, taxonomy, thesaurus or ontology and use those controlled terms to quickly and effectively index large document depositories. As the number of documents exponentially increases with the proliferation of the Internet, automatic indexing will become essential to maintaining the ability to find relevant information in a sea of irrelevant information.