BLOOM supports multilingual tasks primarily through its training data composition, model architecture, and tokenization strategy. The model was trained on the ROOTS corpus, a dataset that includes text in 46 natural languages and 13 programming languages. This dataset ensures broad language coverage, with approximately 30% of the data in English and the rest distributed across languages like Spanish, French, Arabic, Vietnamese, and less-resourced ones such as Basque and Swahili. By training on such a diverse mix, BLOOM learns patterns common across languages and can generalize to tasks in languages it wasn’t explicitly fine-tuned for. For example, a developer could prompt BLOOM in Indonesian and receive coherent responses even if the model wasn’t specifically optimized for that language.
The model’s architecture—a transformer-based design with 176 billion parameters—is optimized for cross-lingual learning. Unlike models that use separate components for different languages, BLOOM processes all languages through shared parameters. This setup allows knowledge learned in one language to transfer to others. For instance, grammatical structures learned from French might improve performance in Italian due to their linguistic similarities. The architecture also avoids language-specific biases by treating all inputs uniformly, enabling consistent performance across the supported languages. Developers can leverage this to build applications that handle multiple languages without needing language-specific models.
BLOOM’s tokenization approach further enhances multilingual support. It uses a Byte Pair Encoding (BPE) tokenizer trained on the same multilingual dataset, which splits text into subword units common across languages. This reduces issues with rare words, as subwords like “-tion” (shared in English and French) or “-mente” (common in Spanish and Italian) are reused. Additionally, the tokenizer prepends language-specific tokens (e.g., <fr> for French) to inputs, signaling the target language to the model. For example, adding <es> before a Spanish prompt ensures the output follows Spanish grammar. This combination of subword sharing and explicit language tagging allows BLOOM to handle code-switching and maintain context across languages, making it practical for developers working on multilingual chatbots or translation tools.