File formats explained

What common file formats are, where they work, and how to open or convert them.

• What is a HEIC file?

  HEIC is the photo format iPhones save by default. What it is, why it saves space, and how to open or convert HEIC files on Windows, Android and the web.

• What is a WebP file?

  WebP is an image format made for the web. What it is, why websites use it, and how to open a WebP file or convert it to JPG or PNG.

• What is an AVIF file?

  AVIF is a newer image format based on the AV1 video codec. What it is good at, where it works, and how to convert an AVIF file to JPG.

• What is a PNG file?

  PNG is a lossless image format with transparency. What it is, when it beats JPG, when it does not, and how to convert or shrink PNG files.

• What is a DOCX file?

  DOCX is the standard Word document format. What is inside a .docx file, how it differs from .doc, and how to open, edit or convert one without Word.

• What is a PDF file?

  PDF keeps a document looking the same on every device. What a PDF is, what it can hold, and how to merge, split or rotate PDF files.