Google has been awarded a Patent For Identifying Transient Content which is able to identify transient content on webpages.
This could refer to any type of content that changes regularly when visitors return to your webpage such as updates which aren’t necessarily relevant to your webpage’s main theme or content which appears on your webpage.
The technology would allow Google to stop indexing pages based upon this kind of content, with the result that any advertisements focusing upon it are also ignored.
Within the description of the Patent for identifying transient data in web pages, Google refers to the ability of search engines to facilitate access to content searched for by users, and providing search results which are relevant to users’ search queries.
The Patent states that “many webpages include transient content (e.g., date, time, weather, etc.) which is not useful in identifying the relevancy of a web page to a search query. Transient data can also lead to improperly targeting advertisements by matching transient content, as opposed to the non-transient content. However, it can be difficult to identify transient content on a large scale without extensive computation”
seomoz has a great analysis on the history of patents identifying updated content and the ways in which fresh content impacts on SEO and rankings.