И and а: two words for and

Russian has two words where English has and: и (i) adds, а (a) compares. Then но (no) is but, and и́ли (ili) is or. The line between и and а does not fall where English puts it, and swapping them changes what you mean.

In order: Mum and Dad are at home. Mum is at home and Dad is at work. It's not coffee, it's tea. It's difficult but interesting. Tea or coffee?

и: plain addition

И adds. Both things are true, and the second sits alongside or follows on from the first:

• Ма́ма и па́па до́ма. - Mum and Dad are at home.
• Он пришёл, и мы пошли́ домо́й. - He arrived and we went home.
• Я зна́ю его́, и он зна́ет меня́. - I know him and he knows me.

It is also the too in me too, and doubled it gives both... and:

• И я! - Me too!
• Он и говори́т, и пи́шет. - He both speaks and writes.

Nothing here surprises an English speaker. The surprise is how much of English and it does not cover.

а: contrast without contradiction

А is the word English lacks. It sets two different things side by side so you notice the difference, but neither cancels the other. The nearest English is whereas or while; in speech English just says and with a bit of stress:

• Ма́ма до́ма, а па́па на рабо́те. - Mum is at home and Dad is at work.
• Я люблю́ чай, а она́ лю́бит ко́фе. - I like tea and she likes coffee.
• Брат до́ма, а сестра́ в шко́ле. - My brother is at home and my sister is at school.

1234

1. 1Она́ чита́ет,
2. 2и он то́же.
3. 3Она́ чита́ет,
4. 4а он игра́ет в футбо́л.

On the left both are reading, so и: he does the same. On the right she reads and he plays football: two people, two different things, so а.

Each sentence says something about two different people and sets them against each other. That is the signal for а. With и instead, a Russian hears two unconnected facts read off a list.

А also does three everyday jobs that English does not do with and at all:

After not X, the correction is always а, never но. On its own, А ты? is and you?, the reply when someone asks how you are.