Google's search spiders react accordingly when a website they have already indexed has posted new material for the search engine to document and assign rankings to. When Google first comes across a website, it applies many grading rubrics to analyze both the substance of the displayed text and the structure of the various tags and meta-data taking place in the background. While it is important for any newly introduced website to make a good first impression on Google's crawlers, whether the website remains high in the listings of Google's SERPs is heavily determined by how much new content is available to parse whenever the crawlers check back on it.
Under some circumstances, a website can remain highly relevant in the SERP rankings even if it consists of content that is never updated. In general, however, a website that adds new content regularly will be rewarded with continued prominence in the rankings because it will be seen as continuously offering reasons for the public to look at the website again and again. The most common model for a website's update schedule is one where entirely new pages get hosted alongside older pages that remain untouched. This is especially the case for websites that follow a blog format, which often treats older pages as historic news items that are preserved for posterity.
Certain other kinds of websites can potentially retain their perceived level of relevance by maintaining the same pages of content at the same URLs while directly adjusting the text currently displayed on them. This is usually trickier to carry out successfully because search spiders register associations based on whatever they record, and future passes made by the crawlers work in terms of those associations. If an existing URL's content is changed so that some of it either is removed or no longer reads the same, then the URL's position in some SERPs will likely suffer even as it rises in other SERPs. On the other hand, both old and new SERP rankings should benefit if changes to existing content prioritize preserving the original substance while placing new material alongside it. For more information click here https://www.reddit.com/r/SEO/comments/la6084/howoftendoyouchangeyourcontent/.