Web3 and Dapps
Programmers/Developers can create applications, named decentralized applications or Dapps, on top of Ethereum to make use of the blockchain technology. This opened a whole new world of blockchain and crypto and came to be known as web3, the next-generation of the web powered by decentralized and interconnected applications.
Web1 was the start of the internet with static pages where people could only read and not interact with websites. Web2 was when sites became interactive and could communicate between each other.
Web3 builds upon Web2 but is decentralized because it runs on the blockchain, meaning it gives people ownership of their data.
Usually Dapps connect to your (crypto) wallet via a Chrome Extension, login, or an API (Application Programming Interface). From there the app can initiate transactions, read data, and perform different actions.