an alphabetical list of words relating to a specific subject, text, or dialect.
When a searcher types a question based query in a search engine, a snippet of content is displayed on top of all results. This is known as a featured snippet. The displayed content under the snippet is from those pages ranking on page 1. This snippet directly answers the question without the searcher having to visit the actual page. An example of such a query is - "How to write a blog post?"