How do people use ETH?

Could you please elaborate on how individuals typically utilize Ethereum, or ETH, in their daily transactions and financial activities? Could you explain the various ways in which ETH is employed, whether it's for making payments, participating in smart contracts, or engaging in decentralized finance applications? I'm also curious to know about the popularity of ETH and its role in the cryptocurrency ecosystem. Additionally, could you discuss any challenges or limitations that users might encounter when utilizing ETH? Thank you for your insights.