SD and microSD cards may all look alike to the untrained eye, but in fact there are different performance levels hidden behind the plastic exteriors - mainly to do with how fast data can be written to the memory.
If you're shooting 4K video or something along those lines then that write performance can be crucial, and will cause all kinds of bugs and crashes if you're not using a card that's fast enough for your latest GoPro video.
To help you make a more informed choice when you're stocking up on memory cards, the SD Association has released a new Secure Digital 5.1 spec, which so far just has one class of card, labelled App Performance Class 1 (or A1).
Play your cards right
To get the A1 badge, a card has to deal with 10MB of data a second, 1,500 random read input/output operations per second, and 500 random write input/output operations per second. Those last two specs are new additions and ensure your card is fast enough to run intensive apps from, if you pop one in your smartphone.
We'd recommend looking out for the A1 label when shopping for a card for your phone, though while the standard gets established, plenty of other cards will work too - just do your research before parting with your cash.
More card classes will arrive further down the line so you don't end up with a dud for your Android smartphone. If you want to save yourself the hassle of picking up and swapping out cards, just go for a phone with lots of internal storage instead.
