WoS identifies and displays the citations - or references - used in articles (not books) and makes these searchable. It also allows you to discover patterns in the way sources are cited.
WoS also makes it possible to rank articles on a topic in terms of how many times an article has been cited, which is a measure of how important it is to a field of study. -- the academic equivalent of social media "likes."
Web of Science can do a kind of search that no other database does as well. This is called a "Related records" search. Clicking on the "Related records" link will create a search of other articles that have used the same references as this author.
The more shared references there are, the more likely the article is going to be relevant, and this is how WoS ranks the results. This creates a kind of network of research on a topic. The articles are likely to be related and help you create the relevant collection of articles you need for a literature review.
Click on the "Related records" search from the full record for the article.
Once you have done a search on, say, a topic, there is a rich assortment of display options. The default is Sort by: Relevance, but below that in the drop down menu are other ways.
Citations: highest first ranks the results by the number of times a paper has been cited by other papers in the WOS database. This can be useful for identifying key papers. It usually takes a fair amount of time to amass a large number of citations, so it is a good idea to see if it is still being cited. A way to see that it Sort by: Usage (last 180 days) or Usage (all time) and check the dates.
Another exceptional sort feature which is only a few years old and apparently not available for all papers in the database is the Citation class, which shows where in sections of other papers a citation has been used by authors
The tab at the top Analyze Results will organize in a graphical display all the papers into the Web of Science categories assigned to them. The categories are also a check box filter on the lower left of the results page.
All the articles in the result are also contained in the Citation Report generated by the tab at the top, which organizes them into timelines of the years they are cited. This is another way to see how papers relate and are used.