Identifying the biggest educational institutions in the world can be based on various criteria such as the number of students, number of branches, and annual revenue. Here are the top 10 educational institutions globally based on these factors:

### 1. **IGNOU (Indira Gandhi National Open University), India**
- **Total Students:** Over 4 million
- **Total Branches:** 67 regional centers and 21 schools
- **Annual Revenue:** Approximately $200 million

### 2. **California Community Colleges System, USA**
- **Total Students:** Over 2.1 million
- **Total Branches:** 116 colleges
- **Annual Revenue:** Approximately $10 billion

### 3. **National University, Bangladesh**
- **Total Students:** Over 2 million
- **Total Branches:** 2,254 affiliated colleges
- **Annual Revenue:** Not publicly available

### 4. **Allama Iqbal Open University, Pakistan**
- **Total Students:** Over 1.3 million
- **Total Branches:** 44 regional campuses
- **Annual Revenue:** Approximately $90 million

### 5. **Anadolu University, Turkey**
- **Total Students:** Over 1 million
- **Total Branches:** Multiple campuses and international programs
- **Annual Revenue:** Approximately $150 million

### 6. **University of California System, USA**
- **Total Students:** Over 280,000
- **Total Branches:** 10 campuses
- **Annual Revenue:** Approximately $39 billion

### 7. **State University of New York (SUNY) System, USA**
- **Total Students:** Over 400,000
- **Total Branches:** 64 campuses
- **Annual Revenue:** Approximately $10 billion

### 8. **K12 Inc. (Stride, Inc.), USA**
- **Total Students:** Over 200,000
- **Total Branches:** Online
- **Annual Revenue:** Approximately $1.5 billion

### 9. **University of Phoenix, USA**
- **Total Students:** Approximately 100,000
- **Total Branches:** Multiple campuses and online
- **Annual Revenue:** Approximately $2.7 billion

### 10. **Liberty University, USA**
- **Total Students:** Over 100,000
- **Total Branches:** Multiple campuses and online
- **Annual Revenue:** Approximately $1 billion

These institutions are known for their significant impact in the educational sector, serving a large number of students globally, having numerous branches, and generating substantial revenues annually.