The UK's Internet marketing and search engine optimisation industry is now worth more than £500m, according to a report by Econsultancy.
The online marketers' site released the SEO Agencies Buyer's Guide on March 19, with figures showing an 18% leap in the SEO market in 2011.
Econsultancy says the year-end value of SEO in the UK was around £514m - up from £436m in 2010.
The 2012 SEO Agencies Buyer's Guide breaks down the valuation: explaining it was calculated using payments to agencies, investment and specialist costs for PR or social media marketing campaigns.
"It's great to see that natural search has developed into a half-billion pound industry in the UK," said Jake Hird, senior research analyst for Econsultancy.
"This also demonstrates the shifting landscape of the SEO marketplace. Now, search practitioners have to deal with elements such as social, mobile and local search, as well as continuing to optimise for other types of content, such as videos and images."
The Econsultancy report also drew a correlation between SEO activity and other kinds of online marketing: with SEO becoming intrinsically important for PR, social media, content marketing and on-page information.
The report also looks at trends, changes and predictions for SEO, such as the focus on Google+, mobile search and increasing integration of SEO with other marketing campaigns.
The guide is aimed at companies looking to hire an SEO agency, with a breakdown of the UK's most successful online marketing firms, together with their costs, services and achievements.
The guide is available to buy through Econsultancy.
News brought to you by ClickThrough – experts in SEO, Pay Per Click Services, Multilingual Search Marketing and Website Conversion Enhancement services.