My 7 year old just asked me what TikTok is

Honest moment here - I don't fully understand TikTok myself but I know it's addictive and probably not great for a first grader. His friend told him about it at school. I said no for now but I feel like I'm just delaying the inevitable. When did you guys introduce social media and how? I want to let him explore but not have him glued to his phone like I see other kids doing.