"Universal search" was launched by Google on May 16, 2007, as an idea that merged the results from different kinds of search types into one. 

Prior to Universal search, a standard Google search would consist of links only to websites.

Universal search, however, incorporates a wide variety of sources, including websites, news, pictures, maps, blogs, videos, and more, all shown on the same search results page.

Marissa Mayer, then-vice president of search products and user experience, described the goal of Universal search as "we're attempting to break down the walls that traditionally separated our various properties and integrate the vast amounts of information available into one simple set of results”.

In June 2017, Google expanded its search results to cover available job listings. The data is aggregated from various major job boards and collected by analyzing company homepages. Initially only available in English, the feature aims to simplify finding jobs suitable for each user.

Google's rise was largely due to a patented algorithm called PageRank which helps rank web pages that match a given search string. When Google was a Stanford research project, it was nicknamed BackRub because the technology checks backlinks to determine a site's importance.

Other keyword-based methods to rank search results, used by many search engines that were once more popular than Google, would check how often the terms occurred on a page, or how strongly associated the terms were within each resulting page.

The PageRank algorithm instead analyzes human-generated links assuming that web pages linked from many important pages are also important. The algorithm computes a recursive score for pages, based on the weighted sum of other pages linking to them. PageRank is thought to correlate well with human concepts of importance.

In addition to PageRank, Google, over the years, has added many other secret criteria for determining the ranking of resulting pages. This is reported to comprise over 250 different indicators, the specifics of which are kept secret to avoid difficulties created by scammers and help Google maintain an edge over its competitors globally.

Because Google is the most popular search engine, many webmasters attempt to influence their website's Google rankings. An industry of consultants has arisen to help websites increase their rankings on Google and other search engines.

This field, called Search Engine Optimization, attempts to discern patterns in search engine listings, and then develop a methodology for improving rankings to draw more users to their client's sites.

SEO encompasses both "on-page" factors (like body copy, title elements, H1 heading elements, and image alt attribute values) and Off Page Optimization factors (like anchor text and PageRank). 

The general idea is to affect Google's relevance algorithm by incorporating the keywords being targeted in various places "on page", in particular the title element and the body copy (note: the higher up in the page, presumably the better its keyword prominence and thus the ranking). Too many occurrences of the keyword, however, cause the page to look suspect to Google's spam-checking algorithms. 

Google has published guidelines for website owners who would like to raise their rankings when using legitimate optimization consultants. It has been hypothesized, and, allegedly, is the opinion of the owner of one business about which there have been numerous complaints, that negative publicity, for example, numerous consumer complaints, may serve as well to elevate page rank on Google Search as favorable comments.