Search engine Optimization - S.E.O. is a marketing practice to rank company web pages higher in search engine result pages (SERP). Some of the popular search engines are Google, Bing, Yahoo etc.

Search engine optimization (S.E.O.) activities are broadly consist of the following:
1. Keyword Research
2. Website changes - technical seo / on site optimization
3. Backlinks - off-site optimization

Another important aspect of S.E.O. is content writing i.e. creation and publishing of quality blog post to get the attention of the target audience. This process further helps in improving the Domain Authority (DA) of a website or a Page Authority (PA) of a particular web page.

In case you want to know the basics of SEO, read this article What's Search Engine Optimization

Also, to learn key SEO metrics jump on to this post Key SEO Metrics