Why is yell.com / Wikipedia.com / BBC.co.uk / etc always at the top of Google?
Well, firstly that depends what you class as ‘nearly always top’. Anyone can take the ‘top’ spot in Google by paying for it via AdWords – but this can turn into an expensive game, very quickly.
The majority of the time, the reason that big sites (Wikipedia, Yell etc) rank well organically is because they:
A) Are old – long established sites tend to be viewed as more trustworthy in Google’s eyes, in the same way that brand new companies are (often unfairly) viewed as fly-by-night and untrustworthy.
B) Are big – using Wikipedia as an example– they don’t pay anything to Google, yet how often do you see a Wikipedia page sitting on top of the rankings? Big sites are more likely to have an answer to a user’s query, and therefore tend to get served up often by search engines.
C) Have a ‘lot’ of links pointing to them. A very quick check tells me that Yell.com currently has around 750,000 other webpages linking back to it. Search engines still count (good quality, relevant) links as part of their ranking algorithms.