What does Hot mean? Just popular?
Context would help a lot, such as the sentence where the word hot was used.
In electronics, it also refers to a wire that has electric potential. This is not much of an issue in small scale robotics since you’re usually not dealing with enough power to make you wonder why you’re waking up on the other side of the room and everyone is staring at you.
On the other hand, it’s probably a concept you should be familiar with before you discover it the hard way.
Its an acronym for the World Champion FCR team Heros Of Tomorrow 
Hot also refers to temperature and spiciness.
“This bowl of soup is hot, I’m going to put some ice cubes in it to cool it down.” ← Temp
“This bowl of soup is hot, I’m going to put some ice cubes on my tongue to cool it down.” ← Spicy
I posted it in Forum Support, so it means the red envelopes instead of the blue ones.
In this context, it means a popular thread, one that has been read more than a certain number of times (I think 250).