Because alt image tags are primarily used by visually impaired website visitors, it’s important to give them the best description possible of your images. That means that you need to give an accurate, detailed description of what’s going on in the image.
Here’s an example using the image above:
OK alt text = Women doing yoga
Better alt text = Women’s yoga class performs tree pose on the beach while waves crash behind them
While the OK alt text describes the image, it doesn’t really paint a clear picture. It is a picture of women doing yoga, but it doesn’t say anything about their location or what they’re doing in yoga class.
Also, avoid using “picture of” or “image of” in your alt tags. Because it’s an alt tag, that you’re describing a picture is already assumed.