The search engine marketing (SEM) world is growing fast but when many companies begin using online marketing they’re unsure if they should use paid search or search engine optimization. One expert says the answer is different for each company.

Writing for the blog Simplefuzz.com, Jeremy Martin says that both pay-per-click (PPC) and search engine optimization (SEO) are "vital" parts of an online marketing campaign, but the answer of which is better depends on what a company is looking to accomplish.

Martin says that with search engine optimization (SEO) the key is consistency. In order for search engine optimization (SEO) to work a site must be constantly building relevant content in order to receive organic search results.

With PPC, sites must not only maintain a budget, but they must constantly test their ads to make sure clicks are being converted. Martin says that testing is the only way to know if changes need to be made to a PPC campaign.

Although the majority of budgets are spent on paid search campaigns, it appears that many companies are turning to search engine optimization (SEO) as a more cost-effective approach to increasing their visibility on the web.

According to a recent study from Internet Retailer, 55.3 percent of retailers said they expect to increase their spending on organic search this year while only 24.2 percent said they plan to increase paid search.