What's the use of 'alt' attribute in the image tag of HTML5?

Question

If the code in HTML5 is: (*** stands for whatever information we need to fill, it is just for example not a keyword)

<img src = "***.jpg" width = "***" height = "**" alt = "*****">

Then here what function does the alt attribute actually do?

Answer 1

From W3Schools

The required alt attribute specifies an alternate text for an image, if the image cannot be displayed.

The alt attribute provides alternative information for an image if a user for some reason cannot view it (because of slow connection, an error in the src attribute, or if the user uses a screen reader).