JPGJPG

JPG 是最通行的有损图像格式——压缩时丢掉人眼不敏感的信息，换来小体积和最大兼容性。

• 适合：照片类内容、对外交付、平台上传。
• 有损阵营：同族的还有 WebP / AVIF——更省体积，兼容性在追（见 无损与有损）。
• 代价：质量掉了不回来；反复保存反复劣化，改稿请留原图。
• 和 PNG 的分工：照片交 JPG，图形截图与透明底 PNG（见 PNG）。

JPG is the most widely compatible lossy image format — compression discards what the eye misses, trading fidelity for small files and universal support.

• Made for: photographic content, external delivery, platform uploads.
• The lossy camp: WebP / AVIF beside it — smaller still, compatibility catching up (see Lossless & Lossy).
• The cost: quality thrown away never comes back; every re-save degrades again — keep the original for re-edits.
• Division of labour with PNG: photos JPG; graphics, screenshots and transparency PNG (see PNG).