Look at your short- and long-term goals to choose whether to focus on organic or paid search (or both). It takes time to improve your organic search rankings, but you can launch a paid search campaign tomorrow. However, there are other considerations: the amount of traffic you need, your budget, and your marketing objectives. Once you’ve reviewed the pros and cons, you can select the search strategy that’s right for you.
The fee structure is both a filter against superfluous submissions and a revenue generator. Typically, the fee covers an annual subscription for one webpage, which will automatically be catalogued on a regular basis. However, some companies are experimenting with non-subscription based fee structures where purchased listings are displayed permanently. A per-click fee may also apply. Each search engine is different. Some sites allow only paid inclusion, although these have had little success. More frequently, many search engines, like Yahoo!, mix paid inclusion (per-page and per-click fee) with results from web crawling. Others, like Google (and as of 2006, Ask.com), do not let webmasters pay to be in their search engine listing (advertisements are shown separately and labeled as such).
In some contexts, the term SEM is used exclusively to mean pay per click advertising, particularly in the commercial advertising and marketing communities which have a vested interest in this narrow definition. Such usage excludes the wider search marketing community that is engaged in other forms of SEM such as search engine optimization and search retargeting.
Facebook Ads and other social media ad platforms, for example, are pay-per-click platforms that do not fall under the SEM category. Instead of showing your ads to people who are searching for similar content like search ads do, social media sites introduce your product to people who happen to be just browsing through their feeds. These are two very, very different types of online advertising.