In biology, an environment is the external set of conditions that interacts with an organism’s genotype to influence its phenotype: its observable physical, behavioral, and physiological characteristics. A genotype is a genetic blueprint, not a complete description of the traits that will be observed. section 7.2.1
From genes to observable traits
Imagine four genes associated with appetite, movement, feet, and skin covering. One combination might describe an insectivore with wings, flight, and feathers. These inherited values illustrate the genotype; the observable characteristics are the phenotype, which also reflects interaction with the environment. section 7.2.1
Figure 7.4 Genotype, phenotype, and taxonomic classification
The figure connects a toy genotype with observable characteristics and classification. section 7.2.1
In reinforcement learning, *environment* has a different, operational meaning: the external world an agent acts in. An action can change its state, produce a reward, and affect later decisions. A model of that world may use deterministic effects or probabilities; for example, a commute by train can lead to an on-time arrival or a missed connection. The agent may observe the complete state or only part of it. section 12.1.1 section 12.1.2







