Emphasis

There are a number of ways to add emphasis in the English language. You can emphasize your statements when you are expressing your opinions, disagreeing, making strong suggestions, expressing annoyance, etc.

Example:

Your homework will be collected on Friday.

In this example, attention is called to what will be collected (homework).

Invert the word order by placing a prepositional phrase or another expression (at no time, suddenly into, little, seldom, never, etc.) at the beginning of the sentence followed by inverted word order. 

Examples:

At no time did I invite him to my party.
Little did he know what she had been planning.  
Seldom have I been so offended.

Note that the auxiliary verb is placed before the subject which is followed by the main verb.

Use the continuous form modified by 'always', 'forever', etc. to express annoyance at another person's action. This form is considered an exception as it used to express a routine rather than an action occurring at a particular moment in time.

Examples:

Her dog is always peeing on my lawn.
Bob is forever late to school.
Juliana was always being bullied by her peers.

Note that this form is generally used with the present or past continuous (he is always doing, they were always doing).

Sentences introduce by 'It', like 'It is' or 'It was', are often used to emphasize a specific subject or object. The introductory clause is then followed by a relative pronoun.

Examples:

It was he who pushed the button.
It is the dog hair that makes him sneeze.

Cleft Sentences: What

Sentences introduced by a clause beginning with 'What' are also used to emphasize a specific subject or object. The clause introduced by 'What' is employed as the subject of the sentence as is followed by the verb 'to be'.

Examples:

What we need is a good lawyer.
What he says isn't always what he does.

Exceptional Use of 'Do' or 'Did'

The auxiliary verbs 'do' and 'did' are not usually used in positive sentences. However, in order to emphasize something we feel strongly these auxiliary verbs can be used as an exception to the rule.

Examples:

No that's not true. He did like her a lot.
I do think you should reconsider your plans.

Note this form is often used to express something contrary to what another person believes.