It's a debating point as old as the hills... Should smartphones have storage expansion slots (e.g. microSD)? From earliest Symbian days to the era of Windows Phone and now Android and iOS, the answer varies according to which manufacturer and model you look at, together with the price point involved. Let's look at the pros... and the cons.

This feature was triggered by the much-publicised decision by Samsung not to include microSD support anymore in its flagship Galaxy S21 series - somewhat shocking, given Samsung's previous stance as the company that gave you every option and check box. Little by little, Samsung is aligning its phones with Apple's iPhones in this regard.

Back in the day (2005-ish, under Symbian), microSD support was more or less ubiquitous - at the time, and perhaps even today, it was cheaper to add Gigabytes with a card than build it into the phone itself. Plus there was the concept of - potentially - a lot of 'local' music, photos or documents needing to both be kept with you and easily transferred to a new phone. Hence taking the card out and putting it into your new phone. Job done. Remember that this was when mobile data was 3G at best and often GPRS - so streaming music or movies, or keeping documents in the cloud were unheard of.

Although not the first phone to eschew cards in favour of internal storage - just buy the capacity you need, the Apple iPhone in 2007 made a big splash about thinking different. The idea was that local music and media came from iTunes on your computer into the built-in storage in the phone and that was that. Just like - as they said at the time - a big iPod.

Windows Phone 7 and 8 toyed with this model too (though Zune software rather than iTunes!) - I'm thinking Lumia 710, 800, 900, though notably non-Nokia phones (e.g. the Samsung Ativ S) did have a card slot, so it wasn't a platform limitation.

Years later, iPhones moved to a cloud-synced media model, of course, when mobile data was good enough, but Apple retained integral storage - which, to be fair, worked better with its 'keep it simple' iOS model for the user.

While from 2009-ish to the current day, the vast majority of Android phones sold have had microSD slots, even if sometimes in place of a 'second SIM' in some dual SIM models. In fact, across all platforms, over the last two DECADES, I'd estimate that well over 80% of smartphones shipped support microSD expansion.

Anyone remember the furore on AAWP over storage when the Lumia 920 came out, in 2012? By then, video was being captured in 1080p and the Lumia 920 had the first instance of OIS in a smartphone. Making it rather good at shooting videos, which then started eating up room in the phone - and auto-cloud backup of videos wasn't really a thing at the time. Add in a few games (also getting large by then) and the Lumia 920's fixed 32GB internal storage was easily filled.

Or was it? We had the same thing with the Lumia 1020 the following year (also 32GB aside from a lucky few with black 64GB units), along with numerous debates on the AAWP podcast as to whether 'one could live with 32GB'. From memory, the jury remained out - one had to be relatively careful not to load much music on - or else be restrained at photo and video capture. 

So when the Lumia 950 arrived, with almost as good a camera setup as the 1020 but with a microSD slot, it was then easy to put in (e.g.) a 128GB card and there, all my music, ALL of it, 50GB worth, plus a dozen video documentaries, all on the tiny sliver of plastic and that left the 950's internal 32GB entirely free for apps and captured content. Ditto my Android-powered Samsungs through the years - the superb S4 and then the even better S9+ in 2018. Card for 'static' media, internal for creating media.

Much better. Or is it? How come we're starting to see a trend at the top end of the smartphone market to have just integral storage and no card slot?

To answer this, I thought an 'All About' table approach would work well.

	Expandable storage (microSD)	Integral storage
Pros	Obviously, if you need more storage for media, it's a piece of cake to pop in a card! Easy to pop the card into a card reader to quickly transfer large file sets - or to juggle them when upgrading a card. The card's file system is absolute, i.e. it's not part of a larger whole, as is the case with a phone's internal disk. So folders and locations in the card's root (etc.) are exactly the same whether seen in a phone app or in a desktop's card reader. i.e. you know where things are to a high degree.	UFS - Universal Flash Storage, now up to v3.1, is way faster than the old eMMC standard and indeed still faster than even the most capable external card. If writing 4K video files, for example, then speed is absolutely of the essence.  Having everything in one storage 'lump' is easier for users, since they never have to think about which disk things are being saved to. Plus, when plugging into a desktop, the phone only appears as one disk rather than two.
Cons	The temptation for most users is to 'buy cheap' when it comes to microSD and it's often the case that a fast phone is hampered by slow external storage (e.g. when writing media) The card slot or tray takes up room, even if slight. Having a slot or tray space is a possible mechanical/durability weakness, again even if slight. Managing what files/apps are 'where' is both a blessing (see 'Pros', above) and a curse. Non-geeks will continually 'lose' files and won't want to keep micro-managing a storage card.	Again obviously, you're stuck with the capacity you buy and if you need more then it's time to sell or switch and buy a larger variant! If you want to get media onto the phone then it's a data cable and desktop affair. Or shuffling things wirelessly by Bluetooth, Wifi or the Cloud. As a result of the above item, setting a new phone up may take longer, since there will be a lengthy media sync stage.

What should surprise you slightly in the table above is how evenly the rows and columns are populated - you really can argue the requirement for microSD both ways. The corollary of this is that it shouldn't matter too much in 2021 - either having a card slot or not each have pros and cons. Most tellingly, integral storage is now so capacious and so cheap that most regular users may not even fill it in the first place.

For example, my three year old Galaxy S9+ is still running like a champ with 40GB used out of its integral 128GB, i.e. 80GB or so free. Yes, I have a microSD card in it as well, with about 50GB of music, but it turns out that, even after three years of use, I could have put this music in the internal disk and not bothered with a card. Space-wise, at least.

My current iPhone 12 Pro Max has 256GB storage and I've used 110GB, including all my music and a truck load of movies and documentaries to watch in odd moments. Plus captured photos and videos. But I somehow doubt that I'll ever hit the full 256GB during my tenure with the phone.

What of my Lumias? Those with 32GB internal disk (most of them, if that) do need a card, of course, for local music, but that 32GB capacity is very much a 2013-2015 thing. It's now 2021 and every flagship should come with 128GB built-in, I contend. While phones further down the food chain, say £500 and below, clearly have to make compromises somewhere and so they save a little money by going lower and still including microSD. So the user still has options (hey, cheaper phones tend to keep the headphone jack as well, but that's an article to be revisited another day!)

In conclusion, if you're researching your next smartphone then don't worry too much about microSD - or the lack of it. You're covered either way. And maybe I shouldn't be too hard on Samsung dropping card expansion in the S21 range after all!

PS. Having written this feature, it rang a bell - I'd visited this subject seven years ago, in 2013. The smartphone world, data bandwidth, media size, and much more, have all changed a lot since then - and the article's conclusion therefore leans differently!