Google changes their search algorithm each and every times. Many of the change is minor and may of the changes is major. Some of algoritm is Google Panda and Google Penguin that affects search results.
Google 2018 Update:
Mobile-First Index Roll-out — March 26, 2018 :-
Google declared that the Mobile First Index was at last "taking off." Since the file has been in trying for a long time, and Google has proposed they are relocating locales step by step, it's hazy how much effect this particular take off had on the general list. Webmastershould start to see warnings inside Google Search Console.
This is the very important algoritm by Google in 2003. The purpose of Hilltop Algorithm is to rank the web pages. First of all identify the important web page then specific to a topic and that linked out to many other sites. It is the linked based algoritm like Page Rank.
In the algorithm Google main priority is Backlinks from the .edu and .gov website.
Hilltop Algoritm can affect ranking todya because It is common practice in SEO today to be cautious about interlinking multiple domains. The implementation of the Hilltop Algorithm is likely the reason for this caution.