So PoH is short for Proof of History, a mechanism that Solana uses to solve the problem of time in blockchain. I just realized why this is so important.

In traditional blockchains, the network has to agree on two things at once: which transactions are valid AND when those transactions occurred. This is very heavy to process. Proof of History solves this in a pretty elegant way—basically by embedding time directly into the blockchain structure.

The difference from Proof of Work is significant. In PoW, miners compete to find the right nonce, which requires crazy amounts of computing power. PoH uses Verifiable Delay Functions (VDFs) that can only be processed sequentially, with just a single CPU core. Because it can't be parallelized, it's easy to verify how long each step takes. This makes PoH a more efficient solution.

Solana combines PoH with Tower Byzantine Fault Tolerance, adding an extra security layer where validators stake their tokens to validate the PoH hash. The result is a network that's lighter and transactions that are truly fast.

The most obvious advantage: Solana's transaction fees are much cheaper than Ethereum, and its throughput is huge thanks to better scalability. That’s why many see Solana as a competitor to Ethereum.

But there are also downsides. The number of Solana validators is still under 1,200, far fewer than other major networks. Plus, its ecosystem is still developing—Solana has around 350 dApps compared to Ethereum’s over 3,000. So in terms of maturity, Ethereum is still ahead.

One thing to remember: PoH is fundamentally based on Proof of Stake, but uses a different timing method. It’s not a completely new consensus mechanism, but an evolution of PoS focused on time calculation. It will be interesting to see how Solana continues to optimize this.