Below are some tips on grammar, spelling, and general technical subjects.
Affect and Effect
This is a very difficult and challenging error, so pay attention to the correct usage whenever you decide to apply one of these words.
Affect should be used when an object, concept, action, etc. causes a change on another object, concept, action, etc. Affect is a verb that describes the action that caused the change. For example, "the editor affected the wiki."
Effect, confusingly, is also used to indicate a object, concept, action, etc. that causes a change on another object, concept, action, etc. However, effect is a noun that describes the change. For example, "the editor's effect on the wiki was positive."
In a very general sense, "affect" describes the action that caused the change, and "effect" describes the change itself.
Advice and Advise
Advice is a noun,
Advise is a verb.
E.g. When I advise you to do something, you can take the advice or leave it.
It's and Its
This is among the most common grammatical errors. It's is a contraction of two words: "it is" or, less commonly, "it has". Its is possessive, like whose, his and hers. "Its computer" means "the computer belonging to it".
Possessive "its" does not need an apostrophe.
E.g. It's flying! Look at its massive wings!
Lose and Loose
Lose is a verb, meaning to lose something (misplaced or to be deprived of); or to lose (fail, the opposite of win). The past tense of to lose is "lost". Loose is an adjective, usually meaning untethered, detached, or not close to something.
E.g. You're going to lose the match if you don't tie your loose shoelaces!
There, Their and They're
There is a place or time-frame. "Over there!" or "There once was..." Their is possessive like whose, his and hers. "Their computers" means "the computers belonging to them". They're is a contraction of two words: They are. "They're playing on the computer at the moment."
E.g. They're building their new house over there.
To, Too and Two
To is a preposition, as in "to the store", or starts of an infinitive, such as "to be". Too indicates that a property of an object is uncomfortably extreme, or can be synonymous to "also". Two is the number 2.
E.g. To do list: to see two of my friends and have too much fun for one day.
We're, Were, Where
We're is a contraction of two words: "we are". Were indicates past tense. Where is a question word, indicating place.
E.g. "We were going to play on the computer - where are we going?"
"We're going to play outside instead."
Who's and Whose
Who's is a contraction of two words: "who is" or "who has". Whose is possessive, like its, his and hers.
Possessive "Whose" does not need an apostrophe.
E.g. "Whose computer is on?" and "Who's still awake?"
You're and Your
You're is a contraction of two words: "you are". Your is possessive, like its, his and hers. "Your computer", the computer belonging to "you".
Possessive "Your" does not need an apostrophe.
E.g. "You're on the computer all the time and your typing speed is extraordinary."