Can I buy ETF directly?

Excuse me, could you please clarify for me if it's possible to purchase an ETF, or Exchange-Traded Fund, directly? I've heard about the benefits of investing in ETFs, such as diversification and lower costs, but I'm not entirely sure how to go about acquiring them. Do I need to go through a broker or can I make the purchase on my own? Also, are there any restrictions or requirements I should be aware of before making such an investment? Thank you for your time and assistance.