Define immigration .

Explanation

**Step-by-Step Text Solution:**

1. **Definition of Immigration**: Immigration refers to the movement of individuals or species from one population to another. This movement is typically motivated by the search for better living conditions or resources.

2. **Purpose of Immigration**: The primary reason for immigration is to enhance survival chances. Individuals may migrate to find more favorable environments that provide better access to food, shelter, or mates.

3. **Impact on Population**: When individuals immigrate into a new population, it leads to an increase in the overall population size. This influx of new individuals contributes to the genetic diversity and vitality of the population.

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