Compact Flash, or CF cards for short, have been on quite the journey over the years, with the original CF card format coming out in 1994 and quickly becoming popular with camera manufacturers as they transitioned from film to digital. CFast cards then came out in 2008 and once the limitations of the CF form factor were outgrown in the 2010’s we transitioned to faster XQD cards in 2011. These were superseded in 2017 by the modern CFexpress cards we see today and take the same form factor as the older XQD cards.
It’s worth noting that CFexpress cards come in Type A versions, with read and write speeds of around 800MB/s or 700MB/s respectively, whereas on Type B cards it's much faster at up to 1800MB/s (read) or 950MB/s (write). They're also physically different sizes and incompatible with each other's system, so it's crucial you pick the correct one for your camera if it has a CFexpress slot.
