A reflowable format is any file format that can be reflowed, or reformatted, to fit the width of a screen. This is in contrast to a fixed-width format, where the text is laid out in columns whose width is fixed, regardless of the width of the screen.
There are two common types of reflowable formats: reflowable markup languages and reflowable document formats.
Reflowable markup languages, such as HTML and XML, are markup languages where the content is structured using tags. The tags define the structure of the document, but they do not define the layout of the document. The document can be reflowed to fit the width of the screen by re-arranging the tags, but the meaning of the document remains the same.
Reflowable document formats, such as PDF and EPUB, are document formats where the content is laid out in pages. The pages can be reflowed to fit the width of the screen, but the meaning of the document remains the same.
