In your opinion, which language is the most difficult in the world?

given that language is made for communication...

the one which enables you to be A that simulates B that simulates C... given that cryptographic leveling condition... well...

just try it for fun!

I’d say Arabic and Japanese.

@MrLizardWizard said ^

I assume by "most difficult", you mean "most difficult to learn for English speakers"? Because I think in that case, you'd be correct. Chinese, Japanese, Russian, Arabic, and Hungarian are the big monsters put up at the top of hardest language lists. But learning Russian, for example, would be 10x easier to learn if your first language was Polish or Bulgarian or something in the same family. The "...

Yes. If a person's native language is Tibetan or some other Sino-Tibetan language, learning Chinese would also be pretty easy for him/her, or at least they'd speak Chinese with some quirks.

由于一次只能上传五个图片,我被迫分开发送。

In short, for native English speakers:

Tier 1: FSI hardest category (about 1100 class hours to reach professional level)

· Arabic: Lots of guttural/pharyngeal sounds, root-based words, written right-to-left, huge differences between Modern Standard Arabic and regional dialects.
· Mandarin: Tones, Chinese characters, measure words, big differences between written and spoken language; little grammatical inflection, but word order, aspect, and vocabulary load are heavy.
· Cantonese: Even more tones, big gap between spoken and written forms, fewer learning resources compared to Mandarin.
· Japanese: Mix of kanji, hiragana, katakana; SOV word order; complex honorific system; lots of omission.
· Korean: Hangul itself is actually easy, but SOV, particles, honorifics, verb forms make it overall still hardest-tier.

Tier 2: Still hard, but slightly easier than Tier 1 or with more resources

· Thai, Lao, Vietnamese: Complex tones and phonology; Vietnamese uses Latin script but tones are tricky, Thai/Lao scripts are difficult.
· Burmese, Khmer: Non-Latin scripts, complex phonology, fewer learning resources.
· Hindi, Urdu, Bengali: SOV, postpositions, gender, case, honorifics, different writing systems.
· Russian, Polish, Czech and other Slavic languages: Cases, aspect, consonant clusters, Cyrillic or special letters.
· Finnish, Hungarian, Estonian: Uralic languages, unrelated to English, many cases, agglutinative, vocabulary hard to remember.
· Turkish: Agglutinative, vowel harmony, SOV.
· Hebrew, Greek, Icelandic: Inflection, writing, vocabulary distance, or conservative grammar.

If we go beyond FSI-taught languages, some can be even more extreme

· Navajo: Polysynthetic, tonal, extremely complex verbs.
· Basque: Isolate, ergative, many cases, unlike any neighboring language family.
· Georgian, Chechen, Adyghe: Caucasian languages, lots of consonants, ergative, complex verbs.
· Inuit, Yupik: Polysynthetic, a single word can be a sentence.
· Khoisan languages: e.g., !Xóõ, Khoekhoe, use click consonants.
· Australian Aboriginal languages: e.g., Warlpiri, Dyirbal, free word order, ergative, complex morphology.
· Many Papua New Guinea languages: diverse language families, few resources, huge differences.

I am ready to answer any question about the Russian language :-) When a child goes to kindergarten, teachers teach them the necessary phrases. If a child lags behind other children in knowledge, a speech therapist and a defectologist work with him. They learn to pronounce letters correctly and express their thoughts correctly. The simplest task is to put 4 pictures in order and come up with a story based on them.

@RemRus said ^

I am ready to answer any question about the Russian language :-) When a child goes to kindergarten, teachers teach them the necessary phrases. If a child lags behind other children in knowledge, a speech therapist and a defectologist work with him. They learn to pronounce letters correctly and express their thoughts correctly. The simplest task is to put 4 pictures in order and come up with a s...

俄语只是T2,中文已经到T1了——普通话纯纯的T1上位,广东话更是T1上位中的上位。

According to the U.S. Foreign Service Institute (FSI), the hardest languages for English speakers to learn are Mandarin Chinese, Arabic, Japanese, Korean, and Cantonese, each requiring roughly 2,200 hours of classroom study (about 88 weeks) to reach professional working proficiency.