If you own an online business, or work in the world of search engine optimization (SEO), then you probably know by now that SEO is not an exact science. Unlike chemistry, there is no formula that guarantees success. It does not suffice to mix the right ingredients together in order to get a substance which will be the same every time. The web changes, it changes a lot, and you need to constantly adapt to what is happening out there. Very few people stick to a single system their whole life, and instead the successful marketers will constantly do experiments and tests in order to see what works, and what no longer does. Here is a list of 31 such experiments, things that were attempted, and whether they turned out to be successful or not.