SEO and SEM are the two main methods of getting impression and ranking on Google search. SEO stands for Search Engine Optimization, which basically means unpaid organic search results for keywords. Where as SEM stands for Search Engine Marketing, which basically means paid search results for an ad group that will normally have a pay per click (PPC) campaign.
The question is; which one is better? This is not an easy question to answer because it can depend on your goal and objectives. If you’re just looking for pure conversions or leads for your business or website then probably SEM is the best way to go. Even though it is paid search it will increase your chances of having someone click on it because it normally appears at the very top of a Google search result page. Plus most who click on ads are already looking for products or services related to your website so you increase your chances of having credible leads.
However when it comes to visibility and influence on the web. There is really nothing better then SEO, because it demonstrates and proves your significance and popularity without any paid search. In other words you could have a paid search that links to a website of company with a lot of money invested into the ad campaigns, that doesn’t necessarily correspond with that companies organic visibility on the web. SEO is the only true way to know how interested others are in your website. So SEO and SEM are both necessary for any successful website but in my opinion SEO is best way to prove and gain true influence on the web