UTM parameters are tags added to the end of a URL that Google Analytics reads to tell you exactly where a visitor came from. Instead of just "social", you get "YouTube description of Video X".
Google Analytics needs utm_source, utm_medium, and utm_campaign at minimum. utm_term and utm_content are optional and used mostly for paid ads or A/B testing bio links.
No. UTM values are case-sensitive, so "Youtube" and "youtube" report as two different sources. Stick to lowercase and use underscores instead of spaces (spring_launch, not "Spring Launch").