Latent semantic indexing, often known as LSI, is a method that search engines employ to comprehend the connection that exists between the words and ideas that are contained on a webpage or in a document.
It is predicated on the notion that words that are semantically connected (having meanings that are comparable to one another) will frequently appear together in a text.

If a website is about “dog training,” for instance, it is likely that phrases like “obedience,” “leash,” and “treats” will occur together on the page.
Because they are all connected to the idea of teaching a dog new behaviours, these words share a semantic relationship with one another.

RankBrain, an algorithm developed by Google, makes use of LSI in order to comprehend the context and content of a webpage.
This enables Google to provide consumers with search results that are more relevant to their queries.

Google’s search algorithm was updated in 2015 to include RankBrain, a machine learning algorithm that plays a role in the ranking of search results.
It is programmed to comprehend the significance of the words used in search queries, as well as the context in which they are used, and to evaluate the relevancy of web pages to those questions.

RankBrain makes use of LSI in a number of different ways, one of which is to determine the connection that exists between the words used in a search query and the information that is presented on a webpage.
For instance, if a user searches for “dog training suggestions,” RankBrain will look for webpages that contain phrases such as “obedience,” “leash,” and “treats,” all of which are semantically relevant to the idea of dog training.

Understanding synonyms and related phrases is another application of LSI that is used by RankBrain.
If a user searches for “dog training,” for instance, RankBrain will also evaluate as relevant results webpages that contain words like “canine training” and “puppy obedience.”

In general, LSI and RankBrain play significant roles in assisting search engines in understanding the meaning of web pages and the context of search requests.
This helps users receive search results that are more relevant to their needs and accurate.