What is an autotroph?

An autotroph ("self-feeder") produces its own food from simple inorganic substances using an external energy source.

• Photoautotrophs: Use sunlight (plants, algae, cyanobacteria — via photosynthesis).
• Chemoautotrophs: Use chemical energy (certain deep-sea bacteria).
• Form the base of every food chain.

Photosynthesis equation: 6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂

Autotrophs make their own food from inorganic substances, forming the essential foundation of all food chains.