There are always people entering and others leaving unemployment. The difference between the number entering and the number leaving will determine if unemployment rise or falls. Although, different countries have different methods of measuring unemployment, which is by the results, is not always suitable to be compared.
The unemployment measured rate of a country is not always accurate as only those who are registered as unemployment will appear in the countries statistics in which they receive unemployment benefits in MEDC's. LEDC's don't have benefits available, so the reliability of the statistics of unemployment rate isn't accurate at all as they are many not registered as unemployed.
There are many reasons in which cause unemployment. Every economy has an 'natural unemployment rate' even when the market clears because the demand for labor and supply of labor is in equilibrium. The three 'natural unemployment' includes frictional, structural and seasonal unemployment.
Frictional unemployment is when workers are switching between jobs, finding the right job or employer finding the right worker and temporarily don't have jobs. They are at a process of searching for a job and are at a process of searching, traveling, applications and interviews for the right job. This is present in every economy because there will always be people entering, re-entering the labor force. Many don't even register as it is not