The American Rubber Plant (Peperomia obtusifolia), also commonly known as a 'Baby Rubber Plant', is a hardy perennial originating from the humid forests of South America. Despite being of a tropical / sub-tropical background, they can thrive incredibly well as a houseplant in indoor environments, making them a great alternative to more picky rainforest plants if you still want to create a lush indoor jungle without the high-maintenance care.
They're recognizable by their rich green foliage, which can also come in prettily patterned variegated varieties. They can show a more bushy appearance, or alternatively can be allowed to trail.
American Rubber Plants are a bit like succulents in that they can store water - this is why they have quite fleshy, thick leaves. For this reason, it's important not to overwater your Rubber Plant, as this could quickly lead to root rot.
This is a tough plant that can handle pretty much everything except from too much water and too little light.
Additionally, you should make sure not to expose your plant to too much harsh, direct sunlight. They still need some light, of course, but American Rubber Plants are used to filtered, dappled light as they grow under taller trees which shelter them from the sun. As such, if your plant spends too much of its day under the sun, it can become damaged and scorched - just like how humans can become sunburnt!
Other than these things to watch out for, American Rubber Plants are very chilled-out and will adapt well to most home conditions. They're fine with average indoor temperatures and humidity, although they do love high humidity, so if you want to keep yours extra happy then try to boost the humidity e.g. by misting. It's also a good idea to place it away from places that are exposed to drafts, and don't put it too close to a heat source as this can dry your plant out.
If you have a variegated American Rubber Plant and you notice that the leaves start to become green, this is a sign that it's not getting enough light. Try moving it somewhere brighter! Old plants often have creeping leaves and stems instead of them standing straight up.
Also, if you're misting your plant regularly to help boost the humidity, make sure not to add too much water - the way that these leaves are shaped a bit like a spoon can lead to excess water collecting and being stored there, which in turn can lead to rot. Just mist enough so that a light spritz covers the foliage.