What is sandbox?

[braketech]

It may seem that the Sandbox is unfair to newly launched websites, but Google created the Sandbox with good reasons. Google was trying to discourage spam sites from quickly reaching the top of Search Results, getting dropped off Google, creating a new site and repeatedly showing up high in Search Results.

[Jeffreyhooft]

The Google Sandbox is much related to a new website being placed on probation, and kept lower than expected in searches, prior to being given full value for its incoming links and content. The Sandbox acts as a de facto experimentation for sites, possibly to put off spam sites from rising quickly, getting banned, and repeating the process.