The <span> tag is used to group inline-elements in a document.

The <span> tag provides no visual change by itself.

The <span> tag provides a way to add a hook to a part of a text or a part of a document.

When the text is hooked in a <span> element you can add styles to the content, or manipulate the content with for example JavaScript.

via HTML span tag.

From The SPAN Tag

Use span tags when you don’t want any changes to the layout other than exactly what you specify in the styles of the span. For example, if you use a <div> or <p> most browsers will add space around the element, because they are block elements.