I first saw a thread and thought i was a couple called Paul & Angela who offered SEO services Then i saw several other threads so i am confused What are they? Thanks
they are monthly lists of websites with higher page rank. using them as backlinks increases your page rank on google. they are a subscription that costs money.
As already mentioned, they are a monthly list of good websites where you can create your links. Now, most of them are profile based links i.e. they are either forums or communities where you can register and make a profile for yourself, which contains a signature and a website field. Filling them with your website link (with appropriate anchor text) is said to boost your SERPS. But a major drawback of these packets is that since many people get them, the websites are flooded with such profiles which the owners then delete, which can render your effort of creating the profile moot.
Backlinks from profiles u drop ur link in the bio section ALL are do follow and most of them are from authority site, thats why are importants, because google bot like this sites Hope i help u