There are no writing topics of any substance that begin with the letter ‘Y’. So under the colloquial title of ‘yanks’, let’s discuss the two variants of English most commonly used in business writing.
Although many think it so, there is no qualitative difference between American English and British English. There are, however, big differences in vocabulary and usage between the two, not just the odd spelling quirk. For example, the UK vocabulary of the motor car — bonnet, bumper, boot — means different things to most Americans, who prefer hood, fender and trunk.
In writing for a US audience, therefore, British companies should swallow their national pride and learn to spell the American way. Otherwise, readers will at best find the materials weird and quirky; and at worst incomprehensible in parts.
The reverse applies, of course!
On the web, everyone can read your stuff. So what should you do?
Write for the majority of your audience. If you’re a UK company whose site is used mainly by UK and European readers, use British English.