Anyone and anything are pronouns taking singular agreement. Any (in the sense under discussion) is a determiner used to reference singular, plural and mass nouns: Has any pupil managed to solve this? // Is there any rice left?
// Have any birds landed yet? How to use anyone and everyone as they are typically used in English Everyone means all of the group. Anyone means all or any part of the group. Original example “ Everyone is welcome to do such and such” means all are welcome.
Anyone Rides Reisterstown Rd, “ Anyone is welcome to do such and such” means all or any part is welcome. In this situation, it makes no difference which word you use. Either word gives every ... meaning - What is the difference between "anyone" and "everyone" in ... The problem is confusing the pronoun anyone (stressed on the first syllable) with the phrase any one (stressed on one), meaning 'choose one'.
Anyone Rides Reisterstown Rd, That's the sense that's grammatical in the first sentence, but it's not the same meaning as anybody, which is negative polarity like anyone (but not any one). That's the problem with written English -- it doesn't represent the sounds and the intonation. The word anyone refers to a single person. If any one is used by itself, it means the same as anyone, but it is preferred for it to be spelled without the space. If any one is used with something else (e.g. any one of them) it can mean something completely different.
In summary, almost all the time you should use anyone, but any one is also an acceptable spelling. Use "anyone" when all elements of a group are involved, but you don't necessarily mean all of them. So "anyone can do it" would mean that everybody in that group could do it, even though it doesn't take them all to do it. syntactic analysis - How to know when to use "someone" or "anyone ...
