I/J : I is for Inside cat.
I'm the one writing about inside cats, and inside vs. outside cats because I have been both.
Our human's first cats were inside-outside cats (cats who lived inside but went outside). One of them was hit by a bus; another was bitten by a parasitic fly. The other went outside until he came back with injuries that may have been caused by a human. He then became an inside only cat. Even then, they did not like to let the cats out at night.
The outside world has a lot of things that are dangerous for cats, such as getting hit by vehicles; meeting a predator (one time when I was sitting on my human's lap, a coyote walked by); parasites like fleas, ticks, and chiggers; cold, wet winters; hot, dry summers; accidental (or malicious) poisoning; nasty neighbors; getting caught in cars; fights with not-so-friendly cats; and other nasty things.
When I was a kitten outside, we had a shed, so we had somewhere we could get out of the rain. Now that I'm inside, I just have to worry about sitting to close to the open window if it starts raining. Well, if there's a bad storm, he'll take me downstairs until it passes. I have lots of cool places to sleep in the summer, and warm places to sleep in the winter. And I don't have to worry about somebody coming around who might want to eat me. My favorite box has the heat vent blow on it; my human likes warm blankets, so I often sleep on his bed.
If I always stay inside, it doesn't matter as much how close we are to a busy road, since I'll never go out to cross it. If I'm inside, I won't get in a fight with a mean kitty who gets me sick. I may get in a fight with another cat who lives here (as I sometimes did when Binx wanted to play tooo rough), but we know the health history of that cat.
Of the farm cats we knew, some died where we could find them. Some came home sick and then died. Some just disappeared. We can hope they found better homes, but we realize that there's a good chance some predator or vehicle got them. I disappeared for a week when I was on the farm; then one morning, he saw me coming up the hill. Truffles disappeared for about a month just before I left the farm, but was back when he came to pick me up. Friendly disappeared while Truffles was gone and was never seen again.
Even though I got more exercise when I was an outside kitty (and that has helped keep me from becoming an overweight inside kitty), I think I like being an inside cat better. I always know that I'll be able to find food when my human is around.