The difficulty of a language depends on what language you’re learning from. For example, for a Chinese learner, Japanese might be easier than English, while for a French learner, English is much easier because of similarities in alphabet, vocabulary, or grammar rules. For English speakers, according to Rosetta Stone, the category IV languages (most difficult to learn) are Arabic, Chinese (Mandarin), Chinese (Cantonese), Japanese, and Korean. This is because there are almost no shared elements between the languages–the alphabets, grammar rules, and pronunciation patterns are completely different–and even the cultural elements that inform the language are not close to each other.