Holy week is recognised in the bible, this is the time Christians use to remember the crucification, death and resurrection of Jesus Christ. They also use this time to remember the time Jesus entered Jerusalem and the last supper with his disciples. At this time Christians are reminded to be holy in whatever they're doing to show respect to the death of Jesus Christ.
During the holy week, they is usually no celebration, because that's the time we mourn the agony of Jesus Christ. The holy week is the time Jesus did one of the actual work he was sent on earth to do by God. He came to die for our sins, thorough his death the sins of man was wiped off and a new begining was gain by humans.
In this case holy week is well recognised by the bible and all Christians are expected to keep that week holy. This is the time we ask God for healing and forgiveness of our sins, because he will be there to listen to us