As the Google competition issues rumble on, various commentators have been grappling with the concept of general versus vertical search. Here at Keplar we have some thoughts on the rise of vertical search and its implications for Google, but we are aware that many people out there don’t yet know what vertical search is, or why it’s important. In this blog post we aim to nail down exactly what vertical search is, so that we can comment more widely on the emerging trends in future posts.

To begin with a definition: unlike a general Web search engine like Google or Bing, a vertical search engine focuses on a specific segment of content. Users visit these vertical search sites to conduct a specialised search for a specific genre of content or category of product. The most commonly known vertical search engines are the price comparison sites, like Kayak or Moneysupermarket.com, where consumers can enter their specific requirements and find a holiday or an insurance deal or similar.

But vertical search is not just used to drive e-commerce sales. There are vertical search engines for images (Google Images), jobs (Trovit Jobs) and dates (Single View) – to paraphrase a certain ad, there’s a vertical search site for pretty much everything.

Many vertical search sites are extremely cash generative. These revenues come largely through affiliate fees – if a user clicks through from Confused.com to Virgin Money and buys travel insurance, then Confused.com makes a referral fee. However there are others which are run at a loss (like Google Images) or as a labour of love; there are also many which don’t make money from the search results but monetize their regular audience through advertising – e.g. Scubadviser.

So vertical search engines are monetizable, but where do they get the actual search results from? There are four different approaches to collecting this data:

1. Pull: scraping – where a vertical search site builds its search index by ‘scraping’ relevant web sites. Scraping is the process of automatically collecting Web information and turning it from unstructured, human-readable data into structured data – perfect for feeding into a vertical search engine. (We wrote a previous blog post on this.)
2. Pull: affiliate networks – where a site imports its search index wholesale from one or more affiliate networks such as TradeDoubler or Commission Junction. These networks hold large databases of products from the merchants they represent – for example the Lastminute.com account within Commission Junction currently has 91 holidays in its database. A vertical search site for holidays could add all of these products to its search index.
3. Push: feeds – where a site builds its search index from merchant-submitted data feeds, typically in XML format. Good examples of this are Kelkoo and Google Product Search.
4. Push-pull: manual – where a vertical search site manually builds up a list of links to relevant sources, through a mixture of techniques including general web searches, community contributions and face-to-face meetings.

If we now understand what a vertical search site is, then how do these fit alongside general web search from Google or Bing? Are they complementary, or competitive? We’ll be discussing these questions and others in our next post in the Curated Web series…

This is the first post in our Curated Web series of posts. The second post looks at how affiliate marketers have re-shaped the purchase funnel online, while the third and final post in the series looks at how these developments threaten Google.