How do I buy shares in AI?

Hello there, I'm interested in investing in AI companies but I'm not quite sure how to go about it. Could you please guide me through the process of buying shares in AI-focused businesses? Are there any specific platforms or exchanges that I should be using? Also, what factors should I consider when selecting which AI companies to invest in? Lastly, are there any potential risks or challenges that I should be aware of before making my investment? I'd really appreciate your insights and advice on this matter.