Is this black-hat SEO technique or something else please sharing you knowledge with me.

Link laundering sites are a blackhat technique in which a lot of sites owned by the same webmaster are all designed to link out to lots of other sites, in exchange for those sites to all be linking back to the single high quality site also owned by the webmaster. The end result is a lot of backlinks all pointing to the same site, while that site hasn't linked out to any. The idea being that Google doesn't detect a reciprocal link exchange.

Link laundering usually involves a network of sites or blogs that the Webmaster owns or has access to. It can be done without a network, but link laundering is easier in many regards if you own or control a network of blogs or websites.

Link laundering sites are a blackhat technique in which a lot of sites owned by the same webmaster are all designed to link out to lots of other sites, in exchange for those sites to all be linking back to the single high quality site also owned by the webmaster. The end result is a lot of backlinks all pointing to the same site, while that site hasn't linked out to any. The idea being that Google doesn't detect a reciprocal link exchange.

Can you explain Link laundering in simple words.It is not clear to me.
Please explain i heard about this first time.