Purim -Behind the mask

B"H
Purim - "Behind the Mask"
It's known that on Purim there is a special happiness, not like other holidays.
What is so special about Purim? why are we so happy on Purim? To the point that it says, משנכנס אדר מרבים בשמחה״, "Our happiness increases when Adar enters". Really we are commanded to be happy all year around. So what is the special on Purim?
Also, there is a Halacha, that we have to give משלוח מנות to one another and מתנות לאביונים, charity to the pour people . How and why is this connected to Purim?
In addition, we have to underrated, why do we dress up on Purim?

There is a Halacha, that if someone reads the Megila from the end to the beginning he did not fulfill the Mitzvah Megila reading. However, if someone reads the Torah from the end to the beginning, he did fulfill the Mitzvah. It also says in the Gemara (Shabbat 88) that on Purim Bnei Yisrael accepted the Torah again. And Rashi explains there, from loving the miracle.
Why specially on Purim?
Why we wearing costumes on Purim?

The explanation is, that the whole story of Megilst Esther is to revel the hidden, to revel the unknown. Hashems name is not mentioned in the Megila. But, throughout the Megila one can see that Hashem is putting everything into place. From the beginning, king Acashverosh came to Shushan even though he was in Babylon, because he wanted a chair like King Salomon, but they couldn't bring it to Babylon, so he moved all his kingdom to Shushan. And all because of "איש יהודי היה בשושן הבירה -one Jewish man, named Mordechai..." Hashem planned everything, that the redemption for the Jewish nation will come from Shushan.
That the king will kill his wife and he will need a new queen. And Esther will be the new Queen. Hashem planed everything ahead. Therfor, one did not fulfill the mitzvah of Megila Reading if he starts from the end. because that way one can not see the chronological order of the story, and how Hashem planned everything ahead to redeem the Jewish nation. Because of that , we dress up on Purim, to show that everyone in world is disguised.

One may think, this person hurt me, that one hit me and so for. But, really it's from Hashem, and people are just disguised to complete the big picture, that we as people don't understand.
From here we can also understand the reason of giving משלוח מנות and מתנות לאביונים to the pour. All year around we are apart at people of hurting us , but on Purim we understand that it's all a part of an unknown plan, and it's all from Hashem. Therefore, after coming to this understanding, we accept everyone, open our hearts for each other and give charity to the pour.
That is the reason we accept the Torah on Purim out of love. Because we realize that Hashem is with us all the time, in all our situations, in the good times and hard times too. This is the reason for the special happiness on Purim.
Purim is special time to ask and pray for everything, ״הפושט יד נותנים לו״. It's a very holy day, and one can get many blessings.