It usually builds an inverted index for fast querying, like:

{
  "word1": [doc1, doc2, doc3],
  "word2": [doc2, doc3, doc4],
  "word3": [doc1, doc3, doc4]
}

1. Tokenization: Tokenization is the process of breaking a piece of text into individual words. This allows you to map from words to documents in the inverted index.
2. Stemming: Stemming is the process of reducing words to their root form. This allows you to match different forms of the same word. For example, "running" and "runs" would both be reduced to "run".

Technologies

ElasticSearch