PPC and SEO together form a marketing strategy known as Search Engine Marketing (SEM).
Pay Per Click (PPC) is a phrase that is used to refer exclusively to Google Ads (AdWords) because that is exactly what it offers – advertisers can list an ad to match a search phrase and pay every time a user clicks on it. Generally speaking, someone looking to start, develop, outsource or optimize an existing AdWords campaign will search for something like “PPC agency NYC” or “PPC management NYC” or even just “AdWords agency NYC”
PPC is a highly successful business model for both the advertiser and publisher themselves. Google is credited with inventing Google Ads (aka AdWords) and being one of the first search engines to not only monetize internet search but also to build an impressively scalable behemoth from it.
PPC differs from SEO in the sense it can be easier, faster, and the most effective way to leverage the first position (result) for any particular search phrase for which Google will allow ads to run. This makes it very appealing for Google Customers to adopt, with the main barrier being cost.