Named entity recognition is a subtask of information extraction. It deals with extracting the names of persons, organizations, locations, expressions of times, quantities, monetary values, percentages etc. from unstructured or semi-structured data such as eMails or web pages.
These are few useful tools and APIs that provide named entity recognition functionality:
- AlchemyAPI: REST API that provides a number of natural language processing (NLP) and information extraction features
- DPpedia Spotlight: Automatically links DPpedia resources
- OpenCalais: NLP API / web service by Thomson Reuters