What is an Ethereum address?

An Ethereum address is a 42-character hexadecimal address derived from the last 20 bytes of the public key controlling the account with 0x appended in front. e.g., 0x71C7656EC7ab88b098defB751B7401B5f6d8976F. Basically, the Ethereum address is the "public" address that you would need to receive funds from another party through the Ethereum network.

Should 0x be added to Ethereum ICAP addresses?

With Ethereum ICAP addresses, the 0x should not be added. I feel like @eth did not answer the question. The 0x is necessary, because it lets the receiver know it's an address in hexadecimal format. Upvoted, yes 0x makes it clear that the address is hex. Highly active question.

What does 0x mean in Ethereum?

The 0x is just a notation to let you know the number is in hexadecimal form. Same as you'd write 042 for an octal number, or 42 for a decimal one. Do Ethereum addresses start with 0x?

Is it safe to send money to an Ethereum address?

Ethereum addresses have a public key and private key. Then, for various reasons, the to keys go into a function that makes a shorted, 20-bytes Ethereum address which is safe to pass around. E.g. send money to my address, "0x123..."