DjVu (pronounced "déjà vu") is a file format primarily designed for storing scanned documents, especially those containing a combination of text, drawings, photographs, and line art. It excels at compressing high-resolution images into small file sizes, making it ideal for archiving and distributing scanned books, magazines, and other documents online. DjVu achieves its compression efficiency through techniques like wavelet-based image compression for the background and foreground layers, and JB2 (DjVu's own compression method) for bi-tonal (black and white) images, which are often used for text. This allows DjVu files to be significantly smaller than equivalent PDF or TIFF files, especially when dealing with color or grayscale images. DjVu is particularly well-suited for documents with complex layouts and a mix of different types of content. While PDF has become the dominant format for document sharing, DjVu remains a viable option, especially for archival purposes and when file size is a critical concern. It is also used in some digital libraries and online repositories.