JPEG本身只有描述如何將一個影像轉換為位元組的數據串流（streaming），但並沒有說明這些位元組如何在任何特定的儲存媒體上被封存起來。JPEG的壓縮方式通常是破壞性資料壓縮（lossy compression），意即在壓縮過程中圖像的品質會遭受到可見的破壞，有一種以JPEG為基礎的標準Lossless JPEG是採用無失真的壓縮方式，但Lossless JPEG並沒有受到廣泛的支援。

一個由獨立JPEG小組（Independent JPEG Group）所建立的額外標準，稱為JFIF（JPEG File Interchange Format，JPEG檔案交換格式）詳細說明如何從一個JPEG串流，產出一個適合於電腦儲存和傳輸（像是在網際網路上）的檔案。在普遍的用法，當有人稱呼一個"JPEG檔案"，一般而言他是意指一個JFIF檔案，或有時候是一個Exif JPEG檔案。然而，也有其他以JPEG為基礎的檔案格式，像是JNG。-PEG itself only describes how to convert a byte image data stream (streaming), but did not explain how these bytes in any particular storage media to be sealed up. JPEG compression method is usually destructive data compression (lossy compression), which means that the quality of the image compression will suffer visible damage, there is a standard based on the JPEG Lossless JPEG is the use of lossless compression methods, However, Lossless JPEG is not widely supported.

One by the Independent JPEG Group (Independent JPEG Group) established additional standards, called JFIF (JPEG File Interchange Format, JPEG File Interchange Format) details how a JPEG stream, output a suitable computer storage and transmission (such as is on the Internet) files. In common usage, when someone called a "JPEG file", generally meaning that he is a JFIF file, or sometimes an Exif JPEG file. However, there are other files in JPEG-based format, such as JNG.