O levels no longer exist in England, their last year was 1987. They were replaced by GCSEs. These are the exams you do at age 16 and often determine whether you are allowed to go on to do A levels, and which subjects you can do. Almost everyone will take at least one GCSE, academically able students (those who will go on to do A levels) will take at least 8 or 9 and often 10-12.

We have primary and secondary schools. Primary: Age 4/5 to 11: Reception, then years 1-6 Secondary: Age 11 to 18: Years 7-13 (though the last two years are often called Lower and Upper 6th Form). In some areas the secondary schools stop after Year 11 and students go on to Sixth Form Colleges. We no longer have O levels. In year 11 students take GCSEs, often 10 or 11 of these. In the Lower 6th form students take AS-level and then do A2-level in the Upper 6th – usually taking 3 or 4 of these. A2 levels are needed to go on to university, in most cases. Some schools in the private sector (i.e. where you have to pay fees) now opt to do the IB course instead of AS/A2 levels.

O-level is Ordinary levels

These are test taken in Secondary Schools in England or any commonwealth country (Years 12 & 13, commonly called the Sixth Form), its the US equivalant to Junior College level education or AS degree. Hopes this helps.

They are optional

O-Levels are now replaced by GCSE’s.

Taken at the end of year 11, they are compulsary, and 5 passes at A*-C are necessary to continue on to A-Levels.