
If your business is in a field that uses certain terms that are spelt differently in US English as opposed to British English, you should be aware that Google will sometimes try and persuade users to use one term or another.
Part of our business is in the ultra competitive field of search engine optimisation. Whilst that spelling appears natural to us (what with being English and all) and even though we're using Google.co.uk, Google clearly feels that this is a misspelling...
One term we're toying with is "search engine optimisation yorkshire". It's not the greatest term, but in a competitive market, a niche like this sometimes has value. Anyway, this is what happens when you type it in on Google.co.uk
I'm sure you can see how this puts us in a minor quandary... do we chase both terms? Stick to our guns and assume that UK users will use the (correct!) spelling? Try to persuade Google that they're wrong?
Actually, our mind is already made up. The UK spelling suits us just fine and hang the consequences! The websites shown for the two results (i.e. "search engine optimization yorkshire" and "search engine optimisation yorkshire") are actually only subtly different. We think Google knows that the two are just equivalent so we're happy not to try and over-optimise our site by trying desperately to write articles that use both spellings (even though we are doing exactly that right now!)
When you're doing your keyword research, try the searches out on Google beforehand. If you find Google suggesting alternate spellings, think long and hard about whether you think there's mileage in it. It may be that there is an easy win in it for you if people are missing this simple trick.
pufft realizing indeed