Yahoo is not a link farm, that's clear or maybe they are but just an accepted one. Some directories look like a link farm to me. Can someone help me with the difference? Thanks.
Some directories are no better than links farms that's for sure... You just need to use your discretion when it comes to submitting to directories... I never submit to a directory that doesn't have sub-categories... some just have main categories and so all the submissions are bundled together on just a few pages rather than being divided up across the site...
The main difference is editorial integrity. Most links hardly bother about editing submissions, catagory relevency, and more importantly they accept all types of websites and blogs. Good quality directories are different. Links are well edited, nice catagory structure, no spam in it.
Directories isolates or group some sites according to their chosen category In Link Farms, bunch of unrelated sites are stocked all-together in the same page
Rand over at SEOMoz wrote a really good post on this a few months ago, http://www.seomoz.org/blog/what-mak...y-and-why-google-penalized-dozens-of-bad-ones
The main aim of link firm to earn money or increase back links by link exchange. You will find all type of links in just a single page or in the categories. The are not caring of the quality and the website look like spam.