Jupyter is convenient for testing, presenting, and sharing code, because ______ contain code, output, and text all in one place.

Jupyter is a versatile tool primarily used for data analysis, visualization, and sharing computational findings. The term "notebooks" in this context refers to Jupyter Notebooks, which are interactive documents that seamlessly integrate code, output, and rich text elements such as Markdown. This format allows users to write and execute code in a cell-based structure, with immediate visualization of results right next to the code that generated them. Additionally, users can annotate their code with explanatory text, making it easy to document the thought process behind their analyses.

This combination of features makes notebooks particularly useful for education, data science presentations, and collaborative projects, as they allow for a cohesive narrative to accompany the computational work. In contrast, documents, scripts, and web pages do not inherently combine code execution with direct outputs and annotations in the same fluid manner as Jupyter Notebooks do. Therefore, the answer highlights the unique functionality that Jupyter Notebooks provide in organizing and presenting code and its resulting data output effectively.