SEO keywords play a pivotal role in boosting your online presence. However, let's delve deeper and read more understand, what exactly is a keyword in SEO.

In online advertising, a keyword is a word or phrase that users enter into search engines when they are searching for a certain service, product or information. Search engine optimization (SEO) heavily is based on the use of these keywords for website ranking.

The magic behind SEO keywords lies in their ability to associate what users are searching for to the content that is available on your website. Wisely using these keywords will help attract the right audience and boost the likelihood of turnover.

Having established the definition of an SEO keyword, let's look at how to use keywords efficiently. Optimizing the use of keywords demands a balance. You'd want to include relevant keywords to appeal to search algorithms but not overuse your content with them.

One way is placing the keyword in your content’s headline. This not only helps in optimization, but also makes your content more relevant to the searcher's query. Consider also using keywords in the metadata and headings of your website, as these are spots where search engines often look.

It's also essential to choose keywords that correlate with your audience. It means understanding their lingo, their internet search habits and their demands.

To conclude, a well-chosen SEO keyword can act as a bridge between the user's query and your online content. It's a critical tool to succeed in the aggressive world of digital marketing. However, success hinges on its effective and balanced use.