Run a Node
Known as a 'client', this software downloads a copy of the Ethereum blockchain and verifies the validity of every block, then keeps it up-to-date with new blocks and transactions, and helps others download and update their own copies.
Ethereum is designed to run a node on average consumer-grade computers. You can use any personal computer, but most users opt to run their node on dedicated hardware to eliminate the performance impact on their machine and minimize node downtime.
Running an Ethereum node may sound complicated at first, but it's merely the act of continuously running client software on a computer while connected to the internet. While offline, your node will simply be inactive until it gets back online and catches up with the latest changes.