Insights, opportunities, and challenges provided by large cell atlases.

The field of single-cell biology is growing rapidly, generating large amounts of data from a variety of species, disease conditions, tissues, and organs. Coordinated efforts such as CZI CELLxGENE, HuBMAP, Broad Institute Single Cell Portal, and DISCO allow researchers to access large volumes of curated datasets, including more than just scRNA-seq data. These resources have created an opportunity to build and expand the computational biology ecosystem to develop tools necessary for data reuse and for extracting novel biological insights. We highlight achievements made so far, areas where further development is needed, and specific challenges that need to be overcome.