Difference between and How to use This and That

It sound really simple but yet it's a little confusing while we use This AND That

THIS & THAT

This is That most common  error and we usually

get confused with while using it.

THIS

When something/someone

is to near you or close to you you can use this,

it could be anything an

object,  a person or a place

THAT

When something/someone is to far form you can use the word that,it could

 be anything an object, a person or a place

when you are pointing a someone or something out you need

to use the word that

THIS AND THAT are singular form so you can use it when talking 

about one person, object or palace 

Lets understand this with some examples

let's assume

you are holding a pencil (a) and there is a pencil (b) on a table

so while showing the pencil (a) to someone you will say 

"this is a pencil"

as you are holding it and it is close to you

and when you are showing the pencil (b) to someone you will say

"that is a pencil"

as you are holding it and it is far from you

let's assume

you and your friend are standing and your aunt comes how will you

introduce them

What would you say?

That is my friend Niya

or 

This is my friend Niya

"This is my friend niya"   is the correct way to say as you have

as you are introducing her and she is standing close to you

let's assume

You are looking to a post and you show it to your friend

What would you say?

Look at this post

or 

Look at that post

"Look at this post"   is the correct way to say as you are holding

the phone and showing it to your friend

let's talk about time 

so usually while talking about past time we use That

and 

while talking about present time we use the word this

That game was amazing last week (past)

or 

This game is amazing, are you having fun ?( Present)

while on a phone 

Hello, this is James. 

(Used to introduce oneself)

and

Is that James?

(while asking for someone on the phone)

while using this and that for more than one person

you should use the plural form

These and those

these are pens (used when there are 2 or more pens)

Those are books on the table (used when there are 2 or more books on the table)

Looking at the examples I hope you understand the difference between This and that

 so now you can use it in your own sentences without any confusion.