EOS is a blockchain, just like Ethereum, Bitcoin and TRON. Like Ethereum, EOS has 

smart contracts, so you can build decentralized applications on it. 

Why is POW built on EOS and not Ethereum?

EOS has two big advantages over Ethereum. First of all, it's very fast. EOS can process over 2000 

of transactions per second. Second, it doesn't charge any transaction fees. This means that all

the operations in the POW Ecosystem are instant and free.

Do I need to pay gas fees?

No. Once you've registered an EOS account, all transactions with EOS assets (including POW) 

are completely free.