In today's scenario a lots of companies using search engine optimization technique to promote their website in search industry. SEO is a technique to promote the website and increase the traffic in search engine results pages (SERPs). We use seo technique to make our brand visible, get high ROI, Usability, User's Stickiness. Some experienced SEO use black hat techniques to increase the traffic for their sites, but this is not a valid technique in search engine industry. Google and other good companies do not allow this black hat technique.

Search Engine Optimization(SEO):
It is the process of improving the volume and quality of traffic to a website from search engines via natural search results.
The purpose of SEO is to make the site better for both search engines and its users.


Search Engine Marketing(SEM):
It is about making your brand visible within the search engines to attract new visitors to your site. Its everything that can be done to utilize the technology of search engine to promote a website and increase its traffic, its stickiness. That's why SEO is a subset of SEM.

There are three main steps of SEM in search engine industry:
Natural or Organic Listing: The pages listing results from a search engine query which are displayed in a sequence according to relevance of match between the keyword phrase typed into a search engine and a web page according to a ranking algorithm used by the search engine.

Paid or Sponsored Listing: Sponsored links are paid ads on the results pages of search engines.

Content Network Listing: A content network, such as those at Google, Yahoo! or Microsoft(Bing) Contextual Search, are advertisements served on web pages next to the content containing the keywords being bid on. Content networks are also known as content ads and contextual networks, but are a form of paid inclusion that is more like cost per thousand than cost per click styles of advertisement.

Benifits of SEO:

Targeted traffic
Increase brand visibility
High ROI
Higher sales
Long term positioning
Cost effective
Accessibility
Usability
Cross Browser Compatibility

SEMPO:
The Search Engine Marketing Professional Organization (SEMPO) is an industry organization for search engine marketing firms. A non-profit professional association, SEMPO was formed in 2003, to promote search engine marketing and provide educational resources to members and consumers. Its sponsors include Google, Yahoo, Microsoft, SuperPages, and Search Engine Strategies. SEMPO's membership includes search engine marketing firms and consultants, Web developers, inhouse marketing professionals, and advertising agencies.