why do we need prefix “data” for custom data attributes in html5

Question

Is there any reason to use data-attribute for custom data attributes on html5 elements? I remember using custom data attributes without using data prefix and I think that did work alright.

Can someone please correct me.

Answer 1

Abridged version of the answer by @Lachlan Hunt to the duplicate question :

• It guarantees there will not be any clashes with extensions to HTML in future editions.
• More convenient DOM API for accessing these attributes from scripts.
• They provide a clear indication of which attributes are custom attributes, and which ones are standardised attributes.