Yes, alt attributes (also known as alt text or alt tags) are important for all images, including logos, on your website for several reasons.
Firstly, alt text improves accessibility. Screen readers use it to describe images to visually impaired users. In the case of a logo, alt text could simply be the name of your company or the descriptor of the logo.
Secondly, alt text is used by search engines to understand what an image is about. While search engines have gotten better at understanding images, the alt text still provides clear information that can improve your SEO.
Here's an example of how you might add an alt attribute to a logo image in HTML:
In this example, 'Your Company Name Logo' is the alt text. This clearly describes the content of the image: it's a logo and it belongs to 'Your Company Name'.
However, make sure that your alt text is accurate and descriptive; don't just stuff keywords into it. If your logo also includes a tagline, it may be appropriate to include that in the alt text as well.