Please can you enlighten me what the acronym XP means. Thank you.
It originates from videogames as the whole Level gaining concept. RPG (role playing games) Usually in a fantasy theme.
You control a fantastic character "warior" or "wizard" and by gathering XP (experience points) by completing game missions (killing enemies, exploring) you gain Level. With each level you unlock/choose new abilities, magics etc. And it's very addicting and fun!
So, smart people used the fun, addiction found in those videogames, and copied that system to create a language learning tool. That's called "gamification".