There are several common image formats that are widely recommended for use on websites. Each format has its own characteristics and best use cases. Here are some of the most commonly used image formats for web content:

1. JPEG (Joint Photographic Experts Group): JPEG is a widely supported and highly efficient format for photographs or images with complex color gradients. It offers good compression, which reduces file size while maintaining reasonable image quality. JPEG is suitable for images that don't require transparency.

2. PNG (Portable Network Graphics): PNG is a popular format for images that require transparency or have simple graphics with sharp edges, such as logos, icons, or illustrations. PNG supports lossless compression, preserving image quality, but the file sizes tend to be larger than JPEGs.

3. GIF (Graphics Interchange Format): GIF is commonly used for simple animations or graphics with limited colors, such as logos, icons, or small animated images. It supports transparency and can have a small file size, but it has a limited color palette and may not be suitable for complex images or photographs.

4. SVG (Scalable Vector Graphics): SVG is a vector-based image format that uses XML-based markup. It's ideal for graphics that require scalability, such as logos or illustrations. SVG images can be scaled without losing quality and are generally smaller in file size compared to raster image formats like JPEG or PNG.

5. WebP: WebP is a modern image format developed by Google. It offers both lossy and lossless compression, providing good image quality at smaller file sizes. WebP is supported by most modern web browsers but may have limited support in older browsers.

The choice of image format depends on factors such as the content of the image, desired quality, transparency requirements, and the balance between image quality and file size. It's important to consider the specific needs of your website and the browsers and devices your audience is likely to use when choosing the appropriate image format.