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There are many projects implementing a so-called side-chain or a new chain which works as 2nd layer solution. What does this mean technically? How can one connect a 2nd layer chain with a root-chain e.g. Ethereum?

If anyone can cut this out in simple terms, or provide useful ressources, it would be very appreciated.

marked as duplicate by Asone, Ismael, Achala Dissanayake, Richard Horrocks, Nicolas Massart Aug 4 '18 at 10:05

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