I put $500 into a cryptocurrency exchange in 2017 and withdrew $1,000 in 2018. How to I report this transaction?

The IRS treats bitcoin and other cryptocurrency transactions as property and not as currency. As such, you must figure gain on the transaction in the same way as with any other type of property. The IRS posted guidance (https://www.irs.gov/pub/irs-drop/n-14-21.pdf) on this matter several years ago, but may revisit the topic, so stay alert.