On erev Yom K’Purim we reach out to our friends and ask for forgiveness.
On Purim we reach out to our friends with Mishloach Manos.
This way they will be more forgiving 7 months later.
Then there is Matanot La’evyonim corresponding to Kaparos which are given to the poor.
On both erev Yom K’Purim and Purim itself we have a major Seudah in the afternoon.
On Yom K’Purim it is the white Kittle to remind us of what the Kohain Gadol wore on Yom K’Purim in the Bais Hamikdosh. On Purim some dress up as Achashverosh and some as the Kohain Gadol.
I wear a Japanese Kimono as a colorful Purim Kittle.
On Yom K’Purim we re-enact the most holy service in the Bais HaMikdosh. The victory of Purim led to the building of the second Bais HaMikdosh.