Difference between "If" and "Had"

[Reborn_Ace]

Hello every one,
I am a new member of this great forum.

Okay, let's get started with my questions.

I have a lot of confusions trying to understand the difference between "If" and "Had". (I do know 'Had' is the past form of 'Have' but when it's used in the below sentence it gives the sentence an entire different meaning.)

For instance, "If you had not come late, we would have reached on time." and "Had you not come late, we would have reached on time."

I have a problem understanding the difference between "Whose" and "Who's" or their usage.

I also have a problem making use of a Colon ":" and/or a Semi Colon ";" in my sentences.

Is there a difference between "Cannot" and "Can not" ? (Do you use a full stop "." mark after a closed quotation mark?)

Do I have to say "People are" or "People is" ?

What is the difference between " and ' ?

Last but not the least, what does 'Affect' and 'Effect' mean? (Could you give a few examples)

A very big thanks to the creators of this forum for giving us an opportunity to clear these 'Brain Eating' doubts. :)

If, there is any grammatical error in my above writing, please let me know, so that I can improve. Phew!

Sorry for this long thread.

[Cerberus™]

If/had: sometimes, "if" is omitted in the type of clause (= part of a sentence) you mentioned. Both "if you had..." and "had you..." mean the same. Note that word order changes when "if" is omitted. Note also that "had" is a subjunctive.

"Whose" means "of whom, of which". Example: "whose house is that?", which means: "to whom belongs that house?".
"Who's" stands for "who is", where the "-i-" is omitted. Example: "who's there?", which means: "who is there?".

A colon indicates that what follows is an explanation of what came before. Typical example: "we sell roses in three colours: white, red, and yellow". Another: "your story about the King of France is nonsense: France has no king".

A semicolon indicates that two sentences are loosely connected. The type of connection is somewhat free for the author to choose. What follows a semicolon might be an explanation, a reason, a comparison, part of an enumeration, an afterthought, et cetera. When in doubt, try to avoid using the semicolon at all. Usually, a full stop "." will do.

Cannot, can ... not and can't mean exactly the same, in can't "-no-" is omitted and in "cannot" the space is omitted, that's all. Cannot is somewhat more formal, can't is slightly casual. But both are quite acceptable and equal to can... not. If can ... not is used without any word in between, you would usually write cannot or can't instead of "can not".

People count as plural, so: "people are".

Between single and double quotation marks there is hardly any difference, though double are somewhat more often used for a quotation within a quotiation. I might say: 'the Minister said "no!" to our proposal'. Either way, you can't really go wrong here, both are perfectly acceptable in any situation.

To affect something/someone means "to have an impact on something/someone"; to effect something means "to cause something to happen, to have something as a (usually desired) result".

[Cerberus™]

I have inserted some comments on grammar into your message. Most of it is quite correct, though!

[Reborn_Ace]

Thank you very much Cerberus™, you were really helpful. :)

Can I use compound adjectives with "-" every time?

[Cerberus™]

The hyphen "-" is used in English to indicate that two words belong together, forming one word. It is only used when there might be confusion without the hyphen: if there is no confusion possible, it is not used.
The rule of thumb with compound adjectives is: use a hyphen only if the c.a. is used attributively; in practice, that means if the c.a. goes before the noun it belongs to. Example:

I bought a two-storied flat. (Attributive: before the noun.)
The flat I bought is two storied. (Predicative: after noun and verb, no possible confusion.)

If an adverb and an adjective go before a noun (in that order), this is not necessarily unclear without a hyphen, so it is not always needed:

I bought a completely redecorated house. (Completely can only be an adverb.)
I bought a little-used car. (Little can be either adverb or adjective.)

Two substantival nouns (words which may have "the") are usually not considered a compound adjective:

I should like to have a telephone protection case. (Telephone and protection are both substantival nouns and the connection between the two can only be read in one way: a case for the protection of the telephone.)

[Reborn_Ace]

Thanks again Cerberus™. Don't know how to appreciate ya :D