Google's John Mueller said this morning on Twitter that if you want your images to rank in Google Image search, it is extremely helpful to Google if you add alt text to your images. The advice itself is not new, it dates back over 10 years ago but this is a nice reminder from a Googler.

John wrote:

Alt text is extremely helpful for Google Images -- if you want your images to rank there. Even if you use lazy-loading, you know which image will be loaded, so get that information in there as early as possible & test what it renders as.

Alt text is extremely helpful for Google Images -- if you want your images to rank there. Even if you use lazy-loading, you know which image will be loaded, so get that information in there as early as possible & test what it renders as. — John ☆.o(≧▽≦)o.☆ (@JohnMu) September 4, 2018

Like I said, this is not new advice but the way John wrote it, it sounds a lot more important than other times. We covered the importance of alt text back in 2017, 2018, and tens years before that, plus many other times. Back in May, Google even updated their image SEO guidelines which talks about the importance of alt text.

Forum discussion at Twitter.