Editing Style guide (section)

===Common grammatical errors===

'''then''' and '''than'''
:Despite their pronunciations being very similar, they are different in meaning.
::'''Then''' is used in one of the three following cases:
:::1. at that time; at the time in question.
::::"I was living in Cairo then."
:::2. after that; next; afterward
::::"She won the first and then the second game."
:::3. in that case; therefore
::::"If you do what I tell you, then there's nothing to worry about."
::::"Well, that's okay, then."
::'''Than''' is used in comparing two elements in a sentence
:::"He was much smaller than his son."
::or in expressions introducing exceptions or contrasts
:::"He claims not to own anything other than his home."

'''its''' and '''it's'''
:'''Its''' is the possessive adjective and possessive pronoun form of the personal pronoun ''it''.
::"He chose this area for <u>its</u> atmosphere."

:On the other hand, '''it's''' is a contraction (shortcut) for '''it is''' OR '''it has'''.
::it is – "It's my fault."
::it has – "It's been a hot day."

'''their''', '''there, '''and '''they're'''
:'''Their''' is possessive, referring to an object, or objects, belonging to a certain number of people.
::"The ball is their property."

:'''There''' is an adverb, referring to a certain position or area.
::"We went on to Paris and stayed there eleven days."

:'''They're''' can also be confused with ''their'' and ''there''. ''They're'' is a contraction for '''they are''' and '''they were''', depending on how the sentence is constructed.
::"The reason that they're going to the store is to buy more milk."

'''should of'''
:The reason people write "should of" when they mean '''should have''' is because the contraction of '''should have''' (should've) is pronounced like "should of". Avoid "should of" like the plague. Instead, write "should have".
::"Those rookie editors made the mistake of writing 'should of' when they meant 'should have'".

'''a herb''' and '''an herb'''
:'''A herb''' is the correct term as the "h" at the start of herb is not silent. American accents clip the "h", which means that ''an herb'' would be incorrect.
:: "Guam is a herb that can be farmed"

'''amount''' and '''number'''
:'''Amount''' refers to a quantity that can be measured. '''Number''' refers to a quantity that can be counted.
::"Higher levels require a greater amount of experience."
::"The maximum number of players in one game is 4."

'''much''' and '''many'''
:As in the above example, '''much''' refers to a quantity that can be measured. '''Many''' refers to a quantity that can be counted.
::"How much experience do you have?"
::"How many people are in your game?"

'''alter''' and '''altar'''
:An '''altar''' is a piece of furniture used in worship. To '''alter''' is to change something.

'''affect''' and '''effect'''
:One thing may '''affect''' (or change) another. The result of an action is its '''effect''' or '''effects'''. Also, to '''effect''' is to produce.

'''your '''and '''you're'''

: The word '''your''' is the possessive form of the word ''you''.

: The word '''you're''' is a contraction of the words ''you are''.
'''duel '''and '''dual'''

You would have a '''duel''' against another person.

You would '''dual'''-wield two swords, or have a '''dual '''personality, meaning you have two sides to you.