Sanitation is waste and what we do with it.
Sanitation is how we manage waste in and around our environments to keep us and our surroundings clean and healthy. This means a lot of things...and sometimes different things to groups.
Generally, these different topics fit into two kinds of waste - bodily and solid. Or, simply, stuff put in toilets and trash.
Bodily excretions (or resource, depending on how you look at it) includes whatever animal bodies excrete - humans included. The focus has often been on feces (or, um, poo), but it also includes period blood, urine, and vomit. Part of this work is also about food safety, ensuring that the food we put in our body and excrete is safe and hygienic (aka, won't make us sick with germs or other hazards).
Toilets are the key way we manage these things that naturally come out of our bodies. And this is a good thing - toilets separate our excretions safely so that our hazardous germs don't get into our environment and make others sick. Once we use the toilet, we use different ways to safely manage the waste through storage and treatment. Other animals may not use toilets like us. However, humans still spend a good amount of time managing how to safely deal with their excretions, as they also have germs.
Trash is anything not coming from our body that we discard and no longer use. This is a big topic - it spans from food scraps to needles and electronics. This stuff doesn't just go away when we're done using them, and some of them can wreak havoc on the environment if left openly exposed. Different kinds of trash decompose over time in different ways, and that can be tricky. We can manage trash in safer ways, which typically includes composting bins, recycling plants, and landfills.
Both of these kinds of sanitation - toilets and trash - are harmful if left unmanaged. Both can make people sick if they aren't safely separated, as they can breed disease and other hazardous substances. Both are also key pollutants in the environment - they can make water dirty and aquatic life, overwhelm soil with unnecessary elements, and are generally unpleasant if left to fester. That's why we have large teams of people working to ensure that this stuff is safely managed and doesn't destroy our health and living spaces.
Departments of sanitation may work on one of these aspects - often both! They typically intersect toilets and trash with street gutters and drains. Street gutters manage stormwater (water that hits the roads during rain), as stormwater picks up trash and other stuff. Often, stormwater also mixes with the waste we flush down the toilet. They may also manage other aspects, like salting and plowing roads for snow - they're already working on managing street gutters, may as well keep the streets clean of snow, too.
We hope that this helps answer the big question about sanitation. Do you have questions that we can answer about this world? Let us know!