How much is a Bitcoin per $1 dollar?

Excuse me, I'm curious about the current valuation of Bitcoin in relation to the US dollar. Specifically, I'm wondering how many dollars would be required to purchase one Bitcoin at this moment in time? Is there a fixed exchange rate, or does it fluctuate depending on market conditions? Could you please provide me with an up-to-date figure, and perhaps a brief overview of how the value of Bitcoin has changed over time? Thank you for your assistance.