What is the difference between the IMG attribute alt and the title?

When we add attributes to the picture, when the beginner, may confuse the difference between the ALT and the title, then the difference between the two, we can from the original intention to see-

The alt word is "Alternate", switching, replacing the meaning. The Common IME switch uses the ALT key to switch between Chinese and English. According to Youdao standard interpretation is as follows:

Title, which is the title, the topic, the caption of an object, such as the article an article title, the role is to summarize the article description.

So, the distinction is good to distinguish, in the HTML document editing IMG tag, Alt is a substitute for IMG can not be displayed when the description of the role, tell people what is here, and the title is a description of the theme of the picture, regardless of whether the image is displayed, as long as there is an IMG tag exists, When the mouse refers to the location of the IMG, the title content will be surfaced.

See Example:

Example one, the picture can be displayed,

Example two, the picture is not displayed,

In short

Alt is the description of objects that cannot be displayed when the picture is not displayed;

Title, is the caption of the picture theme, as long as the IMG tag exists, regardless of whether or not to display the picture, the mouse will appear when stagnant here;