What is stop word in Search Engine Optimisation

Stop words are also known as common words like a, and, how, or, in, the etc. These words not only improve the reader's experience but also make them faster to parse and index web pages. Stop words are used on NLP (natural-language processing) and Internet search engine platforms but are ignored while searching.

For example, when you type "What is Sitemap" on Google's search engine, then Google's algorithm focuses more on "Sitemap" and it shows results on this basis.

For your information, let me tell you that Stop Words was first discovered by Hans Peter Luhn. Which are well known for information retrieval. He has to say about Stop Words that Stop Words does not mean only from English but it is a group of commonly used words in every kind of language.