A keyword is defined as a word or phrase that a user believes is relevant to the information he or she is seeking. Once the user enters the keyword, the search engine starts examining each record in its database to find those documents that match the keywords. A keyword search (as opposed to a concept search) is a search for documents containing one or more words specified by the user.

The Role of keywords within Natural Results
The use of keyword in Meta tags of a site and throughout the website content is an important aspect of search engine optimization (SEO). In particular, the density, the placement and the actual keywords themselves are hotly debated topics. The role of keywords in any good SEO programme is unarguable but the regular change in algorithm by search engines makes it difficult to keep up with the current best practice. However, some good practices that always ring true regardless of how you personally approach SEO.

Keywords: the Key to Paid Search Results

As with organic results, paid results are "matched" to the keywords that consumers type into search engines while looking for goods and services. But the process of selecting keyword for a paid listing campaign is different.

When a marketing professional opts for a paid listing strategy, they are more likely to contract directly with vendors, such as Google or Overture, than to seek advice from a SEM professional.

There is nothing wrong with this approach, but it can often lead to marketers spending their paid listing budget on the wrong search terms. Understandably, vendors tend to provide proposals that aim at achieving maximum click-through-rates—because that's how pay-per-click vendors get paid—but will not necessarily maximize your conversion rates.

This is not to say that vendors will not provide you with targeted results, but it does mean that you may also be paying for many unnecessary clicks from irrelevant keywords. Clearly, those funds spent on irrelevant keywords would be better spent by increasing the budget for the right keywords.

Greater penetration of search results; By optimizing your website’s content to rank well in the organic search results, your website can be found for many keyword phrases and combinations of keywords. Good organic search engine rankings typically take months to achieve, and are fairly easy to maintain on an ongoing basis. Pay per click (PPC) can be implemented quickly–it can also be turned on and off as needed, depending on your company’s budget and current promotions.

Build credibility; Organic search engine rankings provide very high levels of credibility and broad coverage on potentially every search engine worldwide. When a website is listed well in the organic search results, the website usually is found for not only their chosen keywords but many combinations of keyword phrases related to those chosen keywords. It’s those other combinations of related keywords that bring a website a lot of more visibility in the search results, frequently causing a website appear to be found “for everything” related to a certain industry. The results can be staggering–a properly optimized website can appear in the search results more often and for more related keywords than a company who has not done any organic search optimization.

Appearing the paid results also helps to build credibility–just because a searcher doesn’t click on a paid ad and visits the website doesn’t mean they haven’t seen the company’s sponsored listing. Paid listings also can provide some visibility and credibility for certain keywords that aren’t usually obtainable through organic search engine optimization.

High Competitive Keywords – Magnitude in terms of paid search Advertisement

High competitive keywords are those keywords that are more convertible and have the ability of producing more revenue for the search engine through their bidding for the rank.