It’s called a system prompt. It’s a wrapper around the prompt you, the user, writes, which is called the user prompt.
What exactly is being added to the system prompt is a huge part of the “secret sauce” of the AI providers, because it greatly affects the quality and tone of the output. It may also be part of the safety layer of guardrails to stop users from asking about topics the AI providers have deemed taboo (such as biology, in recent news).

Goddamn! I’m sorry people are giving you such a hard time for wanting to collect some data from your rides and use it for planning and stuff.
I want a similar thing for running and it’s really painful. I do not want to subscribe to an app and I don’t want to send my data to some company for monetization. I just want to collect and use the data myself.
I grew up in the 90s and got my first computer in 95. Seeing how awesome the world of software was back then has made me so damn depressed about the subscription hellhole we live in now.