What is the Certified Pool/Spa OperatorÂ® Certification Program? A CPOÂ® Certification provides individuals with the basic knowledge, techniques, and skills of pool and spa operations. This training has helped protect millions of swimmers by reducing hazards at aquatic facilities.
A year is the orbital period of the Earth moving in its orbit around the Sun. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by changes in weather, the hours of daylight, and, consequently, vegetation and soil fertility.
decade. 1  a group of ten. 2  a period of ten years; esp., in the Gregorian calendar. 3  officially a ten-year period beginning with the year 1, as 1921-1930, 1931-1940, etc. 4  in common usage, a ten-year period beginning with a year 0, as 1920-1929, 1930-1939, etc.