The following three pairs of words or phrases cause a lot of confusion, but there are easy ways to learn to distinguish them.
X and Me or X and I?
A lot of people have trouble knowing when to use I and when to use me in sentences such as "John and I had coffee" or "Paul shouted at John and me." Some people think the solution is always to use "I", believing that this sounds more formal. Always using "I", however, not only leads to mistakes but also makes the user sound pompous.
In fact there is a very simple way to decide whether "I" or "me" is right in a particular sentence: simply take out the name of the other person (or people) and the confusion will disappear. For example, is it "Thank you for speaking with John and me." or "Thank you for speaking with John and I."? Take out John's name: "Thank you for speaking with me." (No-one would say "Thank you for speaking with I.")
"The Chief Executive and me had a quick meeting." or "The Chief Executive and I had a quick meeting."? Take out the Chief Executive: "I had a quick meeting." By remembering this rule you need never be confused by this again. Always remember, though, that in formal speech and writing you should put yourself (whether "I" or "me") after the names of the other people.
Your or You're?
Apostrophes always show that letters are missing, except when they indicate possession, i.e. that something belongs to someone. This is a rule you can use to know which form of "your" / "you're" to use. In "you're" something is missing after the "you". It's the letter "a", because "you're" is short for "you are". In "your" there is no apostrophe so nothing is missing. This form of "your" just means that something belongs to "you". It's just like "our", which is never spelled "ou're".
Therefore, if the sentence could be changed so that "you are" replaced "you're", you should use "you're" with the apostrophe: "You're so funny!" is like "You are so funny!" But if you could replace it with "that belongs to you" then you should use "your" with no apostrophe: "I like your new car" is like "I like the new car that belongs to you." Try replacing the "your" / "you're" in the sentence like this to check which one to use, and you won't go far wrong.
Its or It's?
This is a more difficult one because by rights both "it's" meaning "it is" and "its" meaning "belonging to it" should have apostrophes - the first one because the letter "i" is missing and the second one because it indicates possession. However it would be confusing if they were spelled the same way so "its" meaning "belonging to it" has lost its apostrophe. In this case, remember that missing letters always have an apostrophe but words indicating belonging only usually have an apostrophe. For example "ours" and "yours" don't have an apostrophe.
