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.
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 .
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 instead.