What is the meaning of SEO sandbox?

[Search Circus]

The definition of Google Sandbox:

Google Sandbox
Many SEO experts believe that Google ‘sandboxes’ new websites. Whenever it detects a new website, it withholds its rightful ranking for a period while it determines whether your site is a genuine, credible, long term site. It does this to discourage the creation of SPAM websites (sites which serve no useful purpose other than to boost the ranking of some other site). Likewise, if Google detects a sudden increase (i.e. many hundreds or thousands) in the number of links back to your site, it may sandbox them for a period (or in fact penalize you by lowering your ranking or blacklisting your site altogether).

Try NOT to use forums when adding links; sometimes while search engines may not consider it spam to submit links to forums, many forums will consider it spam and eventually reject or deny your link submissions. Submitting links to most forums are considered spam, according to their rules and policies. Submit your link to free and paid link directories, write articles and place your link in the author bio, and exchange links with other related business websites...all of which will build your link popularity naturally.

To read more about what exactly is the Google Sandbox, see here:
http://www.webpronews.com/ebusiness/site...ffect.html