1. Commonly Confused Words
Some words that are spelled differently but sound exactly the same.
Some words that are spelled the same but are pronounced differently.
Some words that do not share the same spelling or pronunciation but are often confused.
These are your commonly confused words.

2. 1. Commonly Confused Words - Homonyms
Words that are spelled differently but sound exactly the same.
Homonyms
Its / It’s
To / Two / Too
There / Their / They’re
Then /Than

3. Example One : Its and It’s
ITS: the possessive pronoun
IT’S: the contraction (short for it is).
It’s common for the cat to lick its claws.

4. Example Two: To, Too, and Two
preposition
Walk to the car (toward)
infinitive indicator
To skate
TOO can mean also or indicate degree
TWO is the number following one
The two girls wanted to go to the skating rink too, but
it was too late.

5. Example Three: Their , They’re, and There
THEIR: (possessive pronoun)
Belonging to them
THEY’RE: (contraction) They are
THERE: (adv) At or in that place (primary def.)
They’re leaving their tired dog over there.

6. Example Four: Then and Than
Than is a conjunction used in comparisons
Then is an adverb denoting time.
Bob noticed that some pigeons were much bigger than others and then he realized they weren’t pigeons at all!

7. Example Five: principal, principle
As a noun, principal means "head" or "chief;" as an adjective, "highest" or "best.“
Principle means "basic truth, law, or assumption." Principle is NEVER an adjective.
The principal author gave the lecture. He acts according to the highest principles.

8. 2. Commonly Confused Words - Same Verbs with Different Sounds
Words that are spelled the same but are pronounced differently.
Life / Live
Everyday / Every day

9. Example One: Life and Live
These words can get very complicated.
LIFE (long vowel sound like pie) is a noun, whose plural is LIVES (long vowel sound)
LIVE is a verb (short vowel sound like in) and the singular present tense of that verb is LIVES (also short vowel sound)
LIVE (with the long vowel like pie) is an adjective that is short for alive.
In his life, the doctor saved many lives.
I live in Miami, but my brother lives in Tampa.
I love to watch Saturday Night Live.

10. Example Two: Every Day and Everyday
To determine which one of these is appropriate,
ask yourself whether you want to say each day
or whether you are looking for an adjective that
means common or ordinary.
Every day is special. Don’t weigh yourself down with everyday concerns.

11. 3. Commonly Confused Words – Different Words
Some words that do not share the same spelling or pronunciation but are often confused.
affect, effect
assure, ensure, insure

12. Example One - affect, effect
To affect is to influence or change.
To effect is to bring about. An effect is a result or an influence.
Ingesting alcohol affects her driving competence. Margaritas effect an undesirable change in his personality; he shouts and tells you that they have no effect on his speech.
NOTE: "Impact" is frequently and inappropriately used as a verb; "affect" is a better choice.
These cuts impact our project.
These cuts affect our project.

13. Example Two: assure, ensure, insure
Assure means "to convince," "to guarantee."
Insure means "to guard against loss."
Ensure means "to make certain."
Assure and ensure are often used interchangeably, but they actually have different meanings.
Assure takes a direct object--usually a person or group of persons. You assure someone that something has been done.
Ensure does not imply that you are giving assurance to someone else. You ensure that something has been done.
Examples:
I assure you of my good intentions.
Please insure this package.
Ensure that you lock your car.

14. Websites for commonly confused words
Commonly Confused Words, A-Z
AskOxford.com
Quizzes
Other sites for Commonly Confused Words

15. DICTIONARIES CCSD ONline Dictionary
Hypertext Webster Dict. search page
The American·British - British·American Dictionary
The Wordsmyth English Dictionary-Thesaurus
On-line Dictionaries
ROGET'S Thesaurus Online
WWWebster Dictionary - Search screen
Dictionary.com