"I am Anna, and this is Tom."
Translation:Я Анна, а это Том.
а is typically used to connect parts of a complex sentence that are opposed to each other. Ia uchitel, a ona vrach (Я учитель, а она врач) - I am a teacher, and she is a doctor.
i (и) is used to connect parts of a complex sentence that correspond to each other or "help" each other in some sense. Ia uchitel, i ona uchitel (Я учитель, и она учитель) - I am a teacher and she is a teacher. Ia skazal privet, i ona ulybnulas' (Я сказал привет, и она улыбнулась) - I said hello and she smiled.
i (и) is also used to list a set of words, just like "and" in English. Анна, Том и Маша - Anna, Tom and Masha.
"а" can be interpreted as "and" or "but" because it is used for contrast. The sentence "Я Анна, а это Том." means that Anna is contrasting herself with Tom. This English sentence is more likely to be used as an introduction, therefore the word "и" would actually be more appropriate. If it were Вера instead of Том, "a" would make more sense because it could be assumed that someone confused Anna with Vera and Anna was correcting them by contrasting the two.
My point was that "Я Анна, а это Том." and "Я Анна, но это Том." are difference sentences. So you can't just translate 'а' as 'but'.
> This English sentence is more likely to be used as an introduction, therefore the word "и" would actually be more appropriate.
"Я Анна, и это Том?" No, we don't say that.
Curious question about 'and' and 'but'. On a previous one it was "Это не Том, а мой папа" where "а" meant 'but'. I got it wrong since I thought it meant "This is not Tom, and my dad"
On this one "а" means 'and' instead of 'but'. In the discussion around a previous example the post had said that ‘И’ means “and” when listing things, ‘а’ is more contrasting. If you can substitute the word “but” for “and” in a sentence, go for ‘a’. But this didn't seem true in this instance. I saw it more as "I am Anna, but this is Tom". An example of if someone called both of you the wrong name.
Не, ... а is a specific expression that needs to be memorized, I think. We don't say "не,... но" except in some idioms.
I'm not sure about this rule: ' If you can substitute the word “but” for “and” in a sentence, go for ‘a’.' At the very least, you have to consider the change of meaning. "I am Anna, and this is Tom" and "I am Anna, but this is Tom" mean different things: the latter would mean that me being Anna somehow contradicts him being Tom. If that's the case, we would use "но" in translation. (And in general, "but" is always translated as "но").
Another example: "I sped up and fell" vs "I sped up, but fell". Different meanings: the former means that I fell because I sped up, the latter that I tried to run faster but failed because I fell. The former will be translated with 'и', the latter with 'но'.