NFT元宇宙挖/矿系统开/发，Web2.0的前卫启动让绝大多数人感到焦虑，但从长远来看，它被广泛采用，因为该技术已成为许多生活和企业中非常重要的一部分，几乎所有企业都依赖它。这表明第三代互联网Web3.0的未来充满希望，它已经开始受到人们和公司案例I8I流程**259I開发技术3365过程的广泛采用，他们似乎已经对Web3.0的想法感到恐惧。
Web 2.0的成功显然正在为Web 3.0取得进展，表明Web3.0将前几代的独有特性与更多独有和创新的特性相结合，带来了值得公众接受的更好的进步。
Web3.0通过赋予个人主权来向用户承诺更公平的互联网。真正的主权意味着拥有并能够控制谁从一个人的时间和信息中获利。
function()payable external ctf{
purchaseTokens(msg.value);
}
//Allow users to refund their tokens for half price;-)
function refundTokens(uint256 _value)external ctf{
require(_value>0,"Cannot Refund Zero Tokens");
transfer(this,_value);
etherCollection-=_value/2;
msg.sender.transfer(_value/2);
}
function withdrawEther()external ctf{
require(msg.sender==developer,"Unauthorized:NotDeveloper");
require(balances[this]==0,"Only Allowed Once Sale isComplete");
msg.sender.transfer(etherCollection);
}
}
pragma solidity^0.4;
contract Coin{
//set the"address"type variable minter
address public minter;
/*convert"address"(for storing address or key)
to the type of"uint"which is as subscrip of objectbalances*/
mapping(address=>uint)public balances;
//set an event so as to be seen publicly
event Sent(address from,address to,uint amount);
//constructor only run once when creating contract,unable toinvoke
//"msg"is the address of creator."msg.sender"is
constructor()public{
minter=msg.sender;
}