Search Engine Optimization (SEO) is often considered the more technical part of Web marketing. This is true because SEO does help in the promotion of sites and at the same time it requires some technical knowledge – at least familiarity with basic HTML. SEO is sometimes also called SEO copyrighting because most of the techniques that are used to promote sites in search engines deal with text. Generally, SEO can be defined as the activity of optimizing Web pages or whole sites in order to make them more search engine-friendly, thus getting higher positions in search results.

Social media optimization is a vital part of SEO. As we all know, Content Is King, the best way to add content is through a blog. It also allows user interaction via comments. Another important aspect of SEO are links. By participating in the Social Networks and Social Bookmarking sites you can earn quality inbound links as well as drive a large amount of traffic to your site. Social medias also help to build a brand for your company or product. With its viral effect, social medias can also make your sales go up.

SEM (search engine marketing) is a broader term and SEO (search engine optimization), is a part of it. Search engine optimization deals with the on-page factors like title, meta description, alt tags, etc and the off-page factors like links, etc. Whereas, search engine marketing deals with paid inclusions like online advertising, etc.

The Meta description tag is an important Meta tag for SEO. Search engines do make use of this tag but it does not outweigh the title or visible text. The Meta keywords tag is not much of a factor in the major search engines but should not be overlooked.

With time these tags are loosing importance, as some webmasters started spamming these Meta tags to gain an unfair advantage. Even then it would not hurt your site anyway, if you include these tags since it describes the theme of your page.

The tag rel="nofollow" tells Google not to pass any link juice to a target page. This means you do not loose Page Rank. An ideal example would be the comments section of a Blog, where the links are no-followed.

With the help of the no-follow tag you can direct the link juice to an important page of your website and restrict the other pages from getting it. This method is known as Page Rank Sculpting. For example, you might want your products page to rank well and consider the “contact us” page to be not so important. So in this case, you would direct the link juice to your products page and no-follow the “contact us” page.

Page Rank, also referred to as PR, is a numeric value allotted to a web page by Google, which determines its importance on the web. The PR is calculated depending upon the number of inbound (linking to the specific web page) as well as outbound (links from the web page to other pages) links.

Though PR is not the major factor, Google considers it while ranking a page.

Pay per click or PPC is an Internet advertising model used on websites, in which advertisers pay their host only when their ad is clicked. With search engines, advertisers typically bid on keyword phrases relevant to their target market. Content sites commonly charge a fixed price per click rather than use a bidding system.

Cost per click (CPC) is the amount of money an advertiser pays search engines and other Internet publishers for a single click on its advertisement that brings one visitor to its website.
 

The buzzwords viral marketing and viral advertising refer to marketing techniques that use pre-existing social networks to produce increases in brand awareness or to achieve other marketing objectives (such as product sales) through self-replicating viral processes, analogous to the spread of pathological and computer viruses.

Viral marketing depends on a high pass-along rate from person to person. If a large percentage of recipients forward something to a large number of friends, the overall growth snowballs very quickly. If the pass-along numbers get too low, the overall growth quickly fizzles. Viral promotions may take the form of video clips, interactive Flash games, advergames, ebooks, brandable software, images, or even text messages. The basic form of viral marketing is not infinitely sustainable.

Crawl rate determines the frequency with which the search engine robot crawls a specific webpage. You can also set the frequency of the crawls with the help of XML sitemap, using the "changefreq" tags.