transformers/docs/source/en/model_doc/mt5.mdx

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# mT5

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## Overview

The mT5 model was presented in [mT5: A massively multilingual pre-trained text-to-text transformer](https://arxiv.org/abs/2010.11934) by Linting Xue, Noah Constant, Adam Roberts, Mihir Kale, Rami Al-Rfou, Aditya
Siddhant, Aditya Barua, Colin Raffel.

The abstract from the paper is the following:

*The recent "Text-to-Text Transfer Transformer" (T5) leveraged a unified text-to-text format and scale to attain
state-of-the-art results on a wide variety of English-language NLP tasks. In this paper, we introduce mT5, a
multilingual variant of T5 that was pre-trained on a new Common Crawl-based dataset covering 101 languages. We detail
the design and modified training of mT5 and demonstrate its state-of-the-art performance on many multilingual
benchmarks. We also describe a simple technique to prevent "accidental translation" in the zero-shot setting, where a
generative model chooses to (partially) translate its prediction into the wrong language. All of the code and model
checkpoints used in this work are publicly available.*

Note: mT5 was only pre-trained on [mC4](https://huggingface.co/datasets/mc4) excluding any supervised training.
Therefore, this model has to be fine-tuned before it is usable on a downstream task, unlike the original T5 model.
Since mT5 was pre-trained unsupervisedly, there's no real advantage to using a task prefix during single-task
fine-tuning. If you are doing multi-task fine-tuning, you should use a prefix.

Google has released the following variants:

- [google/mt5-small](https://huggingface.co/google/mt5-small)

- [google/mt5-base](https://huggingface.co/google/mt5-base)

- [google/mt5-large](https://huggingface.co/google/mt5-large)

- [google/mt5-xl](https://huggingface.co/google/mt5-xl)

- [google/mt5-xxl](https://huggingface.co/google/mt5-xxl).

This model was contributed by [patrickvonplaten](https://huggingface.co/patrickvonplaten). The original code can be
found [here](https://github.com/google-research/multilingual-t5).

## Documentation resources

- [Translation task guide](../tasks/translation)
- [Summarization task guide](../tasks/summarization)

## MT5Config

[[autodoc]] MT5Config

## MT5Tokenizer

[[autodoc]] MT5Tokenizer

See [`T5Tokenizer`] for all details.


## MT5TokenizerFast

[[autodoc]] MT5TokenizerFast

See [`T5TokenizerFast`] for all details.


## MT5Model

[[autodoc]] MT5Model

## MT5ForConditionalGeneration

[[autodoc]] MT5ForConditionalGeneration

## MT5EncoderModel

[[autodoc]] MT5EncoderModel

## TFMT5Model

[[autodoc]] TFMT5Model

## TFMT5ForConditionalGeneration

[[autodoc]] TFMT5ForConditionalGeneration

## TFMT5EncoderModel

[[autodoc]] TFMT5EncoderModel

## FlaxMT5Model

[[autodoc]] FlaxMT5Model

## FlaxMT5ForConditionalGeneration

[[autodoc]] FlaxMT5ForConditionalGeneration

## FlaxMT5EncoderModel

[[autodoc]] FlaxMT5EncoderModel