There are two commonly used storage media that people with Android phones, digital cameras or drones might be aware of -- these are the SD card and microSD card.
At first blush it might seem that all SD cards and microSD cards are the same, but a closer will show that they are not.
If you look at the front of any SD or microSD card, you'll see a whole bunch of symbols and specs, and being able to decipher these will tell you a lot about the card's performance.
After some more text and helpful illustrations, comes this:
OK, so after all this, the question is what cards should you buy?
First off, always buy a name-brand card from a reputable seller. Not only are there a lot of cheapo no-name cards out there, but there are also a lot of counterfeit knockoffs.
If you need a microSD card for a smartphone, then at the minimum it needs to conform to the A2 rating. However, I would buy a card that conforms to both XC I and the U3 UHS speed class.
I usually buy a new micro-SD card for any new phone I put into service, but at this point in time my phone won't take one. I have a number of other devices that use SD cards (small cameras, mostly) and should probably take a look at what is installed in each.
For those of you videoing performances with smart phones, this should be helpful to know.