How do I know if my Ethereum is ERC-20?

Excuse me, but could you please elaborate on how one can ascertain whether their Ethereum holdings are compliant with the ERC-20 standard? I'm quite new to this realm and seeking clarity on this matter. I understand ERC-20 tokens are built on top of the Ethereum blockchain, but I'm unsure of the specific steps or tools I should use to verify the status of my Ethereum assets. Would you be able to guide me through this process, or perhaps point me towards a reliable resource that could assist me in my endeavor? Thank you in advance for your time and assistance.