The Complete Claude Guide
Chapter 04 · WEB

Files, images and local context

Claude can work with material you provide, but attaching a file does not grant access to every folder on your computer. Distinguish chat uploads, Project knowledge and local files accessed by Cowork or Code with permission.

Verified against source on 2026-09-30

Video

Steps

  1. Attach a small non-sensitive file, such as a short PDF or an image. First ask what Claude could read and what is unclear, before requesting conclusions.
  2. For an image or screenshot, identify the area that matters. Small text, scan quality and complex charts can cause reading errors. Check numbers against the original.
  3. Assign roles when supplying several files: "The first file contains data; the second is the report template." Do not assume all material always fits in context.
  4. For local access, open the appropriate workflow and connect only the required folder. Check whether the result is an answer, a downloadable file or a real edit to an existing file.
Common pitfall: Uploading internal material discloses it to the service. Check your organization's rules and use approved sample documents for practice.
Hands-on exercise: Upload a sample PDF and request three facts in a table with page numbers. Compare every cell with the document.
Filmed demo · Video is added in the media phase

Recap

Comprehension check

Does attaching a PDF give access to your whole computer?

Recap

Official sources

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