Search Engine Optimisation (SEO) is the practice of increasing the quantity and quality of traffic to your website through organic search engine results.
Organic traffic is any traffic to your website that you do not have to pay for. (If you pay for advertising, that's Search Engine MARKETING)
There are a multitude of items a website should have to optimise the site so that more people find it just by using their search tools.
Some of these are:
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