In HTML attribute is used to provide extra information about elements.
value.
Any attirbute of an element is defined once within an open tag.
<tag name=value
>Content</tag>
There are hundereds of HTML attribute but some common attributes are.
href attribute is used to provide address information for links element <a></a>. The href full form is hyper reference. By using href attribute you can link hundreds or thousands pages, images and any other documents with each other.
<a href=URL
>text or image for link</a>
Now if you remove your picture from directory and run above code it will show you alt text which is bulb.
Open notepad or any other text editor, follow the following points.
save file with name task.html or task.htm and then open it using any browser and see results.
In example the link name was some text like click me
but in task link name was an image, so you can use any document to link with other document.