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Dear Doctor Umar,
As you may know, EOS is going to be a multiple chains blockchain, every chain being able to communicate with each other. The Mainchain, will hold the EOS "Native Tokens", all the other chains will hold there own "non native" tokens.

Here is a wonderful info-graphic (by Koreos) to better understand the structure of EOS:
EOS-Infinite-scaling.jpg

Here, you will find a second info-graphic (by Koreos) showing us part of the different dapps already announced inside the EOS ecosystem:
eos-dapps.png

Lots of the startup who are going to build dapps and new chains with EOS managed to get some financial help from the VC found. Lots of these startup, as they do not need more money to achieve there plans, decided to distribute there tokens to the EOS holders for free, this is what we call an airdrop.

Here, you will find more info about the EON airdrop.
Have a nice Sunday,
Thierry