SEO VS SEM : difference between Search Engine Optimization & Marketing

SEO VS SEM

 The difference between Search Engine Optimization & Marketing

The last few month, i came across a couple “SEO VS SEM” info-graphics that were comparing SEO (short for Search Engine Optimization) and SEM (short for Search Engine Marketing), the definitions for SEM were contradictory, and i was confused!
Obviously, you should not believe everything you read on the internet, but after some digging, i realized that the same term “SEM” is being used differently by marketers.

Let’s start with official definitions:

Search engine optimization (SEO) is defined as the process of affecting the visibility of a website or a web page in a search engine’s unpaid results — and often referred to as “natural,” “organic,” or “earned” results.
Translation into simple English: this is what you do on your website and on the web to improve your webpage ranking in search results. Website search optimization, consists of making sure that the webpage or website have the necessary data, tags and information to clearly describe what it is all about, this is often done within the code. Web SEO is the practice of linking, referring and pointing to the website throughout the web, this is a pretty complicated task, with lots of traps to avoid.

> SEO service

Search engine marketing (SEM)  is currently defined as a form of Internet marketing that involves the promotion of websites by increasing their visibility in search engine results pages (SERPs) primarily through paid advertising.
Translation into simple English: this is paid advertising that appear on the search result page (usually on top and right side bar).

> SEM service

Truth be told, nowadays, no one knows exactly how to define SEM. Some people, still consider SEM as the umbrella term that groups all the activities affecting Search engines, others consider it as strictly paid search advertising (on Google Adwords, Microsoft Adcenter and Yahoo Searching Marketing ), and yet others consider it a mix to a certain degree of Content Marketing + Social Media Marketing + Paid Search Ads & Management + Reputation Management.

More about:

> Social Media Marketing
> Content Marketing
> Reputation Management


Historically SEM was the collection of strategies to increase the webpage visibility, and that included SEO + paid advertising on search engine + paid listing (back when web directories were important).

Since then the paid listing disappeared, and the paid advertising on search engine have been dominated by Google Pay per click Adwords (search engines now only offer PPC on search results).
But the real reason SEM became equivalent to paid ads, is that paid ads on search engine, are not that simple, in order no to waste your money with little to no results, it is important to optimize the ads display campaigns, and that is done by A/B testing, blocking certain keywords, defining a strict or loose match for keywords and key phrases …
In other words, the paid ads need to be well optimized, and that required continual work.


SEO being handled very briefly by marketing departments: The on site search engine optimization takes a couple days & the offsite SEO takes few weeks.

While Paid advertising was used continuously: Almost all marketing departments advertise on the search engine results, and it is a continuous activity, that never stops in normal conditions.

Thus, the paid advertising managed to squeeze SEO out of the SEM umbrella term.

A quick historical check of the evolution of some terms might shed some light on the situation:

SEM vs SEO trends
Growth of the SEM term

The Google trends graph above, show that SEM took over the PPC (pay per click advertising), PPC being most effectively used on search results, it’s no longer a mystery why many consider SEM as the on search paid advertising.
SEM also took over the growth of PPC and SEO, and that would explain why many still consider the term SEM as an umbrella term that group SEO+Paid advertising.