Holy Week takes place from March 25 till March 31, 2018. Holy Week in Christianity is the last week of Lent and the week before Easter. It includes the religious holidays of Palm Sunday, Maundy Thursday (Holy Thursday), Good Friday, and Holy Saturday. It does not include Easter Sunday.
In Eastern Orthodox tradition, Holy Week starts on Lazarus Saturday, the day before Palm Sunday. (Easter Sunday, for context, is the first day of the new season of the Great Fifty Days, or Eastertide, there being fifty days from Easter Sunday through Pentecost Sunday.) It is followed by Easter Week. (With material from: Wikipedia)