Google sandbox is a tool that used by search engine, it collects the database of new websites and help them to rank top in the search engine. The main purpose of this is to identify the website is created in a spam intention or not.
Google Sandbox is an imaginary area where new and less authoritative sites are kept for a specific time period until they establish themselves of being displayed on the search results. Its generally happen due to building high volume of links in short time.
Good Sandbox? lol this is not a technical term officially used by Google to show any penalty on website. Still let me tell you, always follow white hat SEO practices, and add value to your website visitors, do not spam links, this will keep you away from any penalty.
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