Ascii 로 데이터 표현하기 위한 포맷binary 를 url 로 표현할수 없어서 Base64 방식 활용 Data URLs are composed of four parts: a prefixdata:[<mediatype>][;base64],<data> Data URLsData URLs, URLs prefixed with the data: scheme, allow content creators to embed small files inline in documents. They were formerly known as "data URIs" until that name was retired by the WHATWG.https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs