Mom/in small letters

In this case, you are using Mom as a proper name. Capitalize it.

If you say "My mom is having a birthday", you are only describing a relationship, not using it as a name. Do not capitalize here.

Capital letters are called upper case; small letters are called lower case

Thanks. Roger.

Properly speaking, capital and small letters are majuscule and miniscule respectively, but very few people use these words. More widely understood would be upper case and lower case -- from the ancient typewriter days when each letter striker had both miniscule and majuscule letters on it, the top (upper) one being majuscule.

As far as "mom" and "Mom" go -- I've seen it both ways. However, I'd say that Mom is for the person (just as you would capitalize a real persons name, a proper noun), whereas mom is generic, a state of being.

Of course, mom is slang for mother. In the UK, I believe, it's often spelled mum.

So, it's Happy Birthday, Mom.

Oops, Roger beat me with his brevity!

In Oz too. It's always spelled mum.

I'm indeed grateful that so many of you have responded to my query.

It's spelt 'mum' in Australia too. - When I was 6 I would have got 10 out of 10 in a spelling test except that I read to many Donald Duck comics and used the american spelling. I still hold a grudge against you American imperialist running dogs!

The origin of "upper case" and "lower case" (the explanation I've read) is that historically it started in print shops so long ago that the type characters were set by hand. There were two wooden cases, with a small compartment for each character.

The case that was placed in the upper position, or upper case, held the capital letters, and the lower case held the letters sometimes called small letters. It became the custom to refer to "upper case letters" and "lower case letters".

By the way, I believe China is the place of ancient origin for movable type.

BTW, uppercase and lowercase are each one word. (Webster's)

Yes, I'm being picky.

Roberta, you are quite correct abut "uppercase" and "lowercase" being one word each, when used in reference to letters.

Just for fun, I looked them up in a very old Webster's New International Dictionary (unabridged, around 1913), and they were not single words at that time; apparently they drifted together, as English words often have a way of doing, in germanic fashion.

"Picky" is fine, especially when a close analysis of English is the purpose of this forum. Picky leads to perfection.

In BrE, it is 'upper case' and 'lower case'.