Just a question/observation about plurals in different languages... is it common in most languages to add the letter "s" to a noun to make it plural? I know there are exceptions, like in English we say: one deer/two deer, or one foot/two feet, and in French, sometimes the plural ends with "x", but quite often I have found in English, French, and Spanish that the letter "s" makes a noun plural. Is this common in other languages as well?
The -s suffix is prevalent in languages derived from Latin such as those from the Romance family. When it comes to other languages it actually isn't very common. Other languages might use different suffixes, different forms, reduplication and some might not even have plural marking at all. I'm no language expert, so correct me if I'm wrong folks. :)
It depends on the language. I haven't tried learning every one, so I can't speak for all of them, but I can tell you of the ones on my list, English, Spanish and French are the only ones that add an 's' for plurals, but I wouldn't be surprised if other similar languages did, too.
But other languages do it quite differently. German and Dutch often add an -en or -e (I think Dutch mostly just sticks to -en) at the end and/or has a stem change, Swedish adds -ar or -or, Italian changes the ending to -i or -e, Russian has a whole mess of different plural endings depending on the gender and case, and Japanese and Korean have no inherent plural, it's either inferred from context or specified with other words like 'many'. You do occasionally see -s in some of those, but it's usually just for borrowed words.