I'm an American who lived in the UK for years. Here are 10 things that surprised me.

• I grew up in Massachusetts, but I moved to Scotland several years ago when I married my husband.
• Some foods, like Oreos and potato chips, have different flavors and packaging in the UK.

I grew up in Massachusetts in the US, but I've also spent several years living in Scotland with my husband.

Despite sharing a language (sort of), there are many differences between Britain and America.

Here are a few things I wish I knew before making the move across the pond.

Buying rounds at the pub is a sacred social ritual here

In my experience in the US, everyone generally bought their own drinks when I went to a bar with a group. Buying a round for your friends is a generous gesture, not a requirement.

But in the UK, buying rounds of drinks is an important social ritual. Each person buys a round, and it's considered incredibly poor form to skip out on buying yours.

It also seems to lead to a much tipsier and more expensive pub experience, as you're likely to have at least as many drinks as there are people at the table.

I'm not a big drinker and hate memorizing drink orders, so I wish I'd known about this particular British norm before heading to the pub for the first time.

You can't make your own vitamin D for half the year

According to the UK's National Health Service (NHS), the UK doesn't actually receive enough UVB radiation between October and March for human skin to synthesize adequate amounts of vitamin D from sun exposure.

This fact blew me away. I checked with my GP (primary-care physician), and she confirmed that even if I were to walk around all winter in short sleeves and shorts, UK winter sunlight doesn't contain enough UVB rays for me to make my own vitamin D.

The NHS recommends every person in the UK take a vitamin-D supplement for at least half the year, as it's difficult to get enough from food alone.

The flow of traffic around rotaries is reversed

I can't adequately express the terror that gripped me the first time I went around a British rotary or "roundabout."

Though I knew cars drove on the left side of the road in the UK, it never occurred to me that this quirk might mean that traffic on a rotary would move clockwise rather than counterclockwise.

To this day, every one of my cells starts to scream when we start to go the "wrong" way around on the "wrong" side of the road.

I've noticed people don't tend to introduce themselves right away here

As an American, I'm wired to immediately pummel new acquaintances with a barrage of basic information. It seems normal to share your name in the first minute or two of a conversation.

My British husband finds this compulsion alarming and mildly aggressive. According to him, the Brits tend to introduce themselves at the end of a conversation, if at all.

Instead of saddling up to a stranger at a party and launching into small talk that includes your name and occupation, you're apparently supposed to talk about anything but yourself for as long as possible.

After several hours of conversation and many pints, it may be appropriate to reveal some morsel of personal information.

Dryers aren't standard household appliances

For a nation that seems to see less sun than Pluto, the British seem bizarrely determined to dry all their clothing outside.

Quick bursts of rain aren't uncommon, and it's oddly charming watching people dash in and out of their flats to hang their laundry up to dry between downpours.

We've lived in four different rented flats during my time in the UK, and none of them came with dryers or the hookups that would allow us to install our own.

My husband finds this utterly unremarkable. I find it damp.

The washing machines are also tiny

To further aggravate the laundry situation, the washing machines I've encountered in the UK seem to be made for mice. They're practically pocket-sized.

In the US, I'm used to being able to throw an entire week's worth of laundry in with room to spare. But in the UK, a full load might be several T-shirts, a pair of pants, and a pitiful handful of socks.

I've acclimated to doing three or four loads of laundry a week, but my soul and bulky sweaters ache for a washing machine built like a tank.

The slang is tricky to grasp right away

Every country has its own slang, but the nuances of British slang mean that I'm still constantly embarrassing myself.

Something going "pear-shaped" means something has gone wrong. A "bap" is both a bread roll and a breast. Being "full of beans" means having lots of energy. And of course, "fanny" is slang for female genitalia.

Perhaps most tragically for me, "knob" is British slang for penis.

I wish I'd known this before walking into Ikea with my husband and asking one poor employee if he had a knob bigger than the one I'd brought with me.

The colors for salt-and-vinegar and sour-cream-and-onion chips are reversed

Just when I thought I finally figured out how to navigate a UK grocery store, I found myself inadvertently repeatedly buying the wrong chip (or "crisp") flavor due to one subtle packaging difference.

In the UK, salt-and-vinegar chips are sold in green packaging and sour-cream-and-onion flavored chips are sold in blue bags. But I was used to the reverse in the US.

It's a small difference, but it was seriously annoying until I was able to internalize the new color scheme.

Other familiar food products taste and look different, too

Flavors and ingredient regulations vary widely across the globe, so I suppose it should've come as no surprise that some of the packaged snacks I grew up with would taste different in the UK.

The most noticeable difference I found is between UK and US Oreos. The UK version is a bit more crumbly and the filling has a slightly different texture.

UK versions of popular US chocolate bars also taste a bit different — likely due to the fact that UK chocolate must contain at least 25% cocoa solids, and US milk chocolate only needs to contain at least 10% chocolate liquor.

Talking about the weather isn't awkward

In America, making small talk about the weather is usually considered scraping the bottom of the conversational barrel.

But in the UK, people seem to earnestly want to discuss things like humidity and wind speed.

I wish I'd realized that earlier rather than trying to steer conversations away from weather chat. Now I leave the house each morning armed with strong opinions about the cloud cover.