On-page optimization involves optimizing your all your website pages and all type of content. When you optimize your website for search engines, the first thing you should concentrate is to optimize your website elements. On-page optimization increases your website speed. No one likes a slow loading website. When your website loads slow, people quit your website immediately and go to your competitor's website. Website speed plays an important role in search results. Google rank the websites based on the speed test score simply because Google want to server its users with the best websites in the search results. For higher rank your website should get more than 70% in Google speed test.
Many SEO companies do not know what is on-page optimization. They simply stuff the page titles and meta tags with all key words, they add spammy content, hidden content etc to your pages and try to push your website temporarily in the search results. They do all these black hat techniques and call themselves as a search engine optimization company. These are against Google's seo guidelines. If Google detects these black hat activities in your website, it will permanatly penalize your website and throw your website out of search results. How to choose the Good Seo Company ?
Beware of those fraudulent seo companies. SEO does not stop with link building, back link or social networking. The actual optimization lies in your web pages and page content. Adding the right key phrases in the perfect ration in each page is important part of seo. But there are other optimization tasks which are even more important for improving your website's search engine ranking.
Most of the seo companies who promise you of first page rank in SERP are actually submitting your website to a bunch of web directories or link building websites. They do not optimize your pages because they know only link building. Back linking is an external task in seo. A bad back link can ruin your website's rank. The real important task is to optimize each and every page of your website and every part of your pages. Optimization does not mean adding key phrases. Optimization means making the website lighter and easier for both visitors and search engines.