It depends on the church. Not all churches or religions adhere to the same traditions.
Roman Catholic AnswerThe priest's vestments for the Mass of the Lord's Supper on Holy Thursday are white.
People in Holy week pray and go to Church on Thursday, Friday, Saturday and Ester Sunday.
Its White
Yes it is a holy day of obligation.Actually, Holy Thursday, as well as Good Friday and Holy Saturday, is not a Holy day of Obligation. However, the church urges you to attend mass on these days, and it requires you to attend on Easter.
Off white in color
To signify the Fire Of the Holy Spirit.
Advent- Violet Christmas- White Ordinary time- Green Lent- Violet(rose on 3rd day) Paschal Tridium- White (Holy Thursday), Red (Good Friday), Violet (Holy Saturday), and White (Easter Vigil) Easter- White or Gold Ordinary Time - Green
In the contemporary Western Church, the liturgical color of the Mass of the Lord's Supper on Holy Thursday evening would be white (and, optionally, gold). White/Gold would also be the proper color if the Chrism Mass were offered earlier in the day.The offices (lauds, matins, midday prayers) during the day of Holy Thursday (before the evening Mass) would be violet as during Lent. I don't know what the color would be for night prayer/compline after the evening Mass... I have used violet or white (without further instruction or scruple from the official texts) to close the evening's public adoration with night prayer.For any services held before the Mass of the Lord's Supper on Thursday evening, violet would be worn, as it is still Lent; except for the Chrism Mass in the morning, the color for the White. The vestments for the celebrant at the Mass of the Lord's Supper in the Evening are white. According to the new calendar, since the Second Vatican Council, Lent is over and the Sacred Triduum has begun.
It's not mandatory to go to Mass on Holy Thursday but it is strongly recommended. You learn more about the Holy Triduum and it's relaxing.
For the Catholic Church and many other 'daughter' churches, the holy day 40 days after their Easter Sunday is called Ascension Thursday.
Other names for Holy Thursday are: Maundy Thursday Clean Thursday, Great Thursday, Green Thursday,Holy and Great Thursday, Red Thursday, Sharp Thursday, Sheer Thursday, Shrift Thursday, Thursday of the Mystical Supper.
The Catholic Church says Catholics should not eat meat on Ash Wednesday and all Fridays during the holy season of Lent. Thursdays (including Holy Thursday- the Thursday before Easter Sunday) are not part of the no meat rule. I'm not sure about other religions, only Catholicism.