When it comes to gaining traffic online for marketing, there are generally two approaches that can be taken. PPC (pay per click) advertising is a form of advertising where the advertiser only pays once the advert is clicked on, with the adverts appearing above organic search results on search engine result pages (SERPs). SEO (search engine optimization) looks at gaining traffic by gaining a naturally high ranking on SERPs. Both ways of generating traffic have their pros and cons. Here is a break down of the main points of where PPC is better to use for businesses, who want online marketing, than SEO.
 

PPC Yeilds Quick Results

The great thing about PPC is the fact that anyone can obtain results instantaneously after the campaign is live and running. There is no delay to getting traffic, making it a great way to gain traffic quickly, in the short term. PPC particularly works well for industries where things change very quickly (within hours or days).
 

SEO Yields Better ROI

The problem with PPC is that it costs money, typically more than SEO (especially since SEO can be done for free). For this reason, in the long term, the return on investment (ROI) that PPC brings, when compared to SEO, is generally going to be less, for the same amount of traffic generation.
 

PPC Provides Specific Targeting

Although you could argue that SEO is naturally targeting web users, PPC has extreme targeting to make sure you only pay for traffic that you want. This could include people of a certain age range, demographic in terms of country or area of the country, device they are using, habits and more. This is something that SEO can never do.
 

SEO is Sustainable

The fact that SEO means you can keep getting traffic in the long run should make clear that it is a source of traffic generation that can be considered sustainable. This is compared to PPC where the traffic stops as soon as your advertising campaign stops.
For many advertisers, this will be the main reason to choose SEO. Having traffic in the long run that keeps coming in will also reduce the cost of marketing for the future too.
 
Ultimately, it really does depend on your specific situation as to whether PPC will be better or SEO. For some people, even the combination of both PPC and SEO can produce synery-like results, due to the fact that PPC makes up the short term traffic gains and delay that is inherently the case with getting traffic from SEO.
If you are unsure which is best for you, explore and test both. You can take an educated guess as to which will be better for you. However, without quantifiable data to back up your reasoning, you cannot simply choose one over the other, unless you are very sure.