Holidays in Switzerland are categorized according to established common local holidays, regional observances and seasonal celebrations. Interestingly, the only official public holiday recognised in Switzerland is Swiss National Day observed on 1 August. In Switzerland, the Federal Statute on International Private Law (PILA) determines the terms of employment contracts. Although the employment contracts are not necessary by law, but most of the employers and employees still prefer to have written agreements setting forth terms of employment, salary, benefits and entitlement to common local holidays and territorial observances.