Final answer:
To be or become second nature means a behavior that is learned and has become almost automatic. Examples include the route from home to school becoming automatic over time, distinguishing it from innate or instinctive behaviors like a spider spinning a web.
Step-by-step explanation:
To be or become second nature to somebody means a behavior that is learned and has become so well-practiced that it is almost automatic. An example of learned behavior is the route you take from your house to school. Initially, you consciously learn the route, but after doing it many times, it becomes second nature and does not require conscious thought each time you take it.
In contrast, an innate behavior is instinctive and is determined by genetic makeup rather than learned through experience. For instance, a spider spinning its web doesn't need to learn or practice this skill; it happens naturally due to the spider's instincts.