Google's motives for not sharing their algorithm are likely rooted both in the proprietary nature of their business model and the susceptibility of the algorithm to 'black hat' tactics & loophole exploitation were it to ever be revealed in full. Still, there are some helpful resources available to get to an idea of how changes to their algorithm affect users. Google's page on How Search Works provides a good starting point for understanding how queries are sorted. Moz's Google Algorithm Change History provides a more detailed break down of how updates to the algorithm have impacted Google search over time. Further, experimentation with varying tactics on similar pages is a great litmus test. This is where knowledgeable expertise from SEO and SEM specialists can be invaluable. Hope this was helpful, - Charles
