What is OKX or Binance?

Could you please elaborate on what OKX and Binance are? I've heard these names frequently in the realm of cryptocurrency and finance, but I'm still a bit hazy on their exact functions and roles. Are they exchanges where people can buy and sell digital currencies? Do they provide additional services like wallets or staking options? I'm also curious about their reputation in the industry, how secure they are, and any notable differences between them. Could you shine some light on these aspects for me? Your insights would be greatly appreciated.