The word sanctification refers to the act of making holy or setting apart as special. The word is used five times in the Authorized Version of the New Testament (1 Corinthians 1:30, 1 Thessalonians 4:3,1 Thessalonians 4:4, 2 Thessalonians 2:13, and 1 Peter 1:2).
To sanctify means “to set apart for special use or purpose,” and “to make holy or sacred,” and etymologically from the Latin verb 'sanctificare' which in turn is from sanctus “holy” and facere “to make.”
When an object or place is made holy, usually a ceremony is performed. Then people see that it is a special object or place and treat it with respect. A person may also be "set apart for special purpose", as when a priest or pastor is ordained.
Sanctification can also refer to the process by which a person becomes a good moral person, or someone with a close relationship to God. This may not include any ceremony. Persons who achieve this holiness are sometimes called Saints. Some churches have a list of saints who have been recognized as having been especially holy persons.
Generally in Protestant teaching, all Christians are considered saints. All are expected to become people who are close to God and who live a life like that which Jesus taught. Reading the Bible, prayer, worshiping God and Jesus and telling others about their faith are important in becoming sanctified.