Is ERC20 an ICO?

Excuse me, as a cryptocurrency and finance expert, I have a question regarding the terminology used in this industry. Specifically, I've come across the terms ERC20 and ICO quite frequently, but I'm still unclear about the relationship between them. Could you please elaborate on whether ERC20 is an ICO? I understand ERC20 refers to a technical standard for tokens issued on the Ethereum blockchain, but does it inherently imply an Initial Coin Offering (ICO) or are they separate concepts? Clarifying this distinction would be greatly appreciated.