ELI5 Horse Racing - what’s the role of the jockey?

Can you explain the role of a jockey during a horse race? Why do horses start side by side in a race instead of a staggered start like in human races? How does horse racing differ from dog racing, and why is the latter often frowned upon? How betting odds work in horse racing? ... we explain like I'm five Thank you to the r/explainlikeimfive community and in particular the following users whose questions and comments formed the basis of this discussion: k0fi96, anecdotallyextant, alienfreaks04, the_camperdave, gameofchat, theicklestone, sceneofshadows, rsdancey and yourdadsbff To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Join us on Twitter: https://www.twitter.com/eli5ThePodcast/ or send us an e-mail: ELI5ThePodcast@gmail.com