Type effectiveness refers to the strengths and weaknesses of different types in a game or system, often seen in role-playing games like Pokémon. Each type can have advantages or disadvantages against other types, influencing the outcome of battles. For example, a Water type is strong against Fire types but weak against Electric types. Understanding type effectiveness helps players strategize their moves and choose the right characters or abilities. By knowing which types are effective against others, players can maximize their chances of winning encounters and make informed decisions during gameplay.