MUM (Multitask Unified Model) is Google's advanced AI model announced at Google I/O 2021. Google described MUM as 1,000 times more powerful than BERT, with the ability to understand and generate language, process multiple types of information simultaneously (text, images, video, and audio), and work across 75 languages at once. MUM represents a major leap in Google's ability to understand complex, multi-part queries that require synthesizing information from diverse sources.

How MUM Differs from BERT

While BERT improved Google's understanding of natural language in text-based queries, MUM operates at a fundamentally higher level. MUM is multimodal — it can process and understand images, audio, and video in addition to text. It is also multilingual in a deeper sense: MUM can transfer knowledge across languages, finding relevant information in documents written in languages different from the query language. Google demonstrated this with the example of a user uploading a photo of a mountain and asking "Can I use these hiking boots for this trail?" — a query that requires understanding visual context combined with text.

Key point: MUM is not primarily a ranking algorithm — it is more of a task-understanding and knowledge synthesis system. Google uses it to understand complex information needs and identify subtopics to surface in search features like "Things to know" and topic-based query refinements.

MUM's Impact on Search

MUM has been applied in several areas of Google Search:

  • Understanding complex, multi-part queries that previously required multiple searches
  • Generating "Things to know" panels that surface key subtopics about a subject
  • Refining search queries by identifying related topics users may want to explore
  • Enabling visual search capabilities in Google Lens
  • Improving cross-language information retrieval

Why It Matters for SEO

MUM signals the direction of Google's evolution toward understanding comprehensive information needs rather than individual keyword queries. For SEOs, this reinforces the importance of creating truly comprehensive content that addresses topics in depth, including all relevant subtopics and angles — because MUM helps Google identify gaps between what a searcher needs and what a single page provides. As AI models like MUM become more central to search, topical authority and complete content coverage become increasingly valuable SEO strategies.