The apostrophe means that the -es that was used to form the possessive of words in older English was shortened by leaving out the e. Geoffrey Chaucer would have spelled the word "computeres" if computers happened to have been around in the 1300's.
It could also be used to contract "computer is" such as you might do when you yell "The computer's on fire!"
The word there's is a contraction for there is. The apostrophe substitutes for the i in is.
If you mean as an abbreviation of 'old', then the apostrophe would be at the end of the word (ol'), because the apostrophe shows that the 'd' at the end of the word has been omitted.
"Theres" isn't actually a word. "There's" is a word, and is a contraction of "There is". "Theres" must have an apostrophe to mean anything at all in the English language.
It means there is already an "s" at the end of the word
The apostrophe in "nor'wester" is a contraction of the word "northerly." It is often used in nautical and meteorological contexts to describe a strong wind blowing from the north or northwest.
it means the word is singular possessive
An apostrophe after a word means there is possession of something. Example: the girl's doll (the doll of the girl) Anna's pink dress (the pink dress of Anna)
NO, if you typed "viruses'" (viruses with an apostrophe) it would mean "The viruses' (more than one virus's) something.
An apostrophe followed by an "s" is used to indicate possession or ownership of something. For example, "Mary's book" indicates that the book belongs to Mary. It is also used to create contractions, such as "can't" for "cannot."
The apostrophe in "cyclist" would be placed before the last letter when indicating possession: cyclist's.
there is no apostrophe
It is not a word. It is two words: "it will". The "i" in "it" is not pronounced, and that is why there is an apostrophe there. You will quite frequently see the letter "t" with an apostrophe in front in Shakespeare, and it always means "it".