C3, C4, and CAM photosynthesis represent distinct pathways for carbon fixation, each adapted to minimize water loss in different environmental conditions.

C3 photosynthesis is the most prevalent form and is found in the majority of plant species. In this pathway, carbon dioxide ($\text{CO}_2$) is fixed into a three-carbon molecule, which subsequently contributes to the synthesis of glucose. However, C3 plants experience reduced efficiency in hot and arid environments due to increased water loss through transpiration.

C4 photosynthesis offers a more efficient alternative that has evolved in response to the challenges of hot and dry climates. In this pathway, $\text{CO}_2$ is initially fixed into a four-carbon molecule. This molecule is then transported to specialized cells, where it is converted back into $\text{CO}_2$ for utilization in the Calvin cycle. This mechanism not only enhances photosynthetic efficiency but also significantly reduces water loss.

CAM (Crassulacean Acid Metabolism) photosynthesis is a specialized variant of C4 photosynthesis, predominantly found in succulent plants such as cacti and agaves. In CAM plants, the stomata open at night to absorb $\text{CO}_2$, which is then stored as a four-carbon molecule. During the day, the stomata remain closed to conserve water, and the stored $\text{CO}_2$ is used in the Calvin cycle.

In conclusion, while C3 photosynthesis is the most common pathway, C4 and CAM photosynthesis are specialized adaptations that enhance efficiency and minimize water loss in hot and dry environments.