Most Commonly Confused Words List in English

Here is a list of most commonly confused words of English... 

Advice / Advise
Advice - a noun: you can give someone an advice. His advice was very useful.
Advise - a verb: He advised me

Affect / Effect
Effect - a result or the power to produce a result. Effect can also be a verb meaning to bring about or execute.
Affect - verb that means to have an influence on

Aisle / Isle
Aisle - a passage between rows of seats
Isle - a an island

All together / Altogether
All together - applied to people or things that are being treated as a group
Altogether - used to mean entirely.

Altar / Alter
Altar - a sacred table in a church
Alter - to change

Allusion / Illusion
Allusion - an indirect reference.
Illusion - a misconception.

Alternately / Alternatively
Alternately - in turn; one after the other:
Alternatively - on the other hand; one or the other.

Appraise / Apprise
Appraise - assess
Apprise - inform

Assent / Ascent
Assent - agreement
Ascent - climb up

Beside / Besides
Beside - next to
Besides - also

Born / Borne
Born - Having Born
Borne - Carried

Breach / Breech
Breach - to break through
Breech - the back part of a gun barrel

Broach / Brooch
Broach -  to raise a subject for discussion
Brooch - a piece of jewellery

Climactic / Climatic
Climactic  - forming a climax
Climatic - related to climate

Complacent/Complaisant
Complacent - smug and self-satisfied
Complaisant - willing to please

Complement / Compliment
Complement - something that completes or makes up a whole
Compliment - an expression of praise or admiration

Defuse / Diffuse
Defuse - to make a situation less tense
Diffuse - to spread over a wide area

Discreet / Discrete
Discreet - prudent, circumspect, or modest
Discrete - separate or individually distinct

Dual / Duel
Dual  - having two parts
duel - a fight or contest between two people

Elicit / Illicit
Elicit - to draw out.
Illicit - unlawful.

Farther / Further
Farther - to or at a more distant point
Further - to or at a greater extent or degree

Few / Less
Few - small in number. It is used with countable objects:
Less - small in amount or degree. It is used with uncountable objects

Foreword / Forward
Foreword - an introductory note or preface
Forward - toward the front

Hoard / Horde
Hoard  - a store
Horde - a large crowd of people

It's / Its
It's is a contraction for it is
its is the possessive form of it

Practice / Practise
Practice - the use of an idea or method; the work or business of a doctor, dentist, etc.
Practise - to do something repeatedly to gain skill

Principal / Principle
Principal - a person who holds a high position or plays an important role
Principle - a rule or standard

Stationary / Stationery
Stationary is an adjective that means fixed or unmoving
Stationery is a noun that means writing materials