<p>
    학교종이 땡땡땡땡땡땡땡땡땡땡땡땡땡땡땡땡땡땡땡땡땡땡땡땡땡땡땡 어서 모이자.
    선생님이 우리를 기다리신다.
</p>
<p>
    There's a veryveryveryveryveryveryveryveryveryveryveryvery
    longlonglonglonglonglonglonglong-longlonglonglong sentence.
</p>
p {
    background-color: gold;
    word-break: /* value */
}
CSS 데모: word-break 데모 버튼을 클릭해 보세요!
selector {
    word-break: /* value */
}
/* 키워드 값 */
word-break: normal;
word-break: break-all;
word-break: keep-all;
word-break: break-word; /* 더 이상 사용되지 않는 값 */

/* 글로벌 값 */
word-break: inherit;
word-break: initial;
word-break: revert;
word-break: revert-layer;
word-break: unset;
<!DOCTYPE html>
<html lang="ko"> <!-- html 태그에 lang 속성으로 페이지의 기본 언어 지정 -->
    <head>
        <meta charset="UTF-8">
        <title>한글에서 word-break 설정하기</title>
    </head>
    <body>
        <h1>한글에서 word-break 설정하기</h1>
        <p>
            한글에서 가독성을 고려한다면
            <br>
            word-break 속성의 값을 keep-all로 설정하는 것이 좋습니다.
        </p>
    </body>
</html>
:lang(ko) {
    word-break: keep-all;
}
<div class="container">
    <a href="https://example.com/css-word-break-%ec%86%8d%ec%84%b1-%ec%98%ac%eb%b0%94%eb%a5%b8-%ec%9d%b4%ed%95%b4%ec%99%80-%ec%82%ac%ec%9a%a9-%eb%b0%a9%eb%b2%95/" target="_blank">
        https://example.com/search?q=css+word-break&newwindow=1&sca_esv=02577cfd3aace2eb&source=hp&ei=3lQtadyIN-Pd1e8PoPyzyAk&iflsig=AOw8s4IAAAAAaS1i7vIdEU9E2wWtsmACszXYOsVPQDzP&oq=css+wor&gs_lp=Egdnd3Mtd2l6Igdjc3Mgd29yKgIIADIFEAAYgAQyBRAAGIAEMgUQABiABDIFEAAYgAQyBRAAGIAEMgUQABiABDIFEAAYgAQyBRAAGIAEMgUQABiABDIFEAAYgARIwCNQAFjOEXAAeACQAQCYAb4BoAHWB6oBAzAuN7gBAcgBAPgBAZgCB6AC9QfCAgsQABiABBixAxiDAcICERAuGIAEGLEDGNEDGIMBGMcBwgIEEAAYA8ICCBAAGIAEGLEDwgIHEAAYgAQYCsICCxAuGIAEGLEDGIMBmAMAkgcDMC43oAfyI7IHAzAuN7gH9QfCBwUwLjUuMsgHFg&sclient=gws-wiz
    </a>
</div>
:lang(ko) {
    word-break: keep-all;
}
.container {
    width: 240px;
    padding: 1em;
    background-color: gold;
}
브라우저에서 실제 표시된 모습
<div class="container">
    <a href="https://example.com/css-word-break-%ec%86%8d%ec%84%b1-%ec%98%ac%eb%b0%94%eb%a5%b8-%ec%9d%b4%ed%95%b4%ec%99%80-%ec%82%ac%ec%9a%a9-%eb%b0%a9%eb%b2%95/" target="_blank">
        https://example.com/search?q=css+word-break&newwindow=1&sca_esv=02577cfd3aace2eb&source=hp&ei=3lQtadyIN-Pd1e8PoPyzyAk&iflsig=AOw8s4IAAAAAaS1i7vIdEU9E2wWtsmACszXYOsVPQDzP&oq=css+wor&gs_lp=Egdnd3Mtd2l6Igdjc3Mgd29yKgIIADIFEAAYgAQyBRAAGIAEMgUQABiABDIFEAAYgAQyBRAAGIAEMgUQABiABDIFEAAYgAQyBRAAGIAEMgUQABiABDIFEAAYgARIwCNQAFjOEXAAeACQAQCYAb4BoAHWB6oBAzAuN7gBAcgBAPgBAZgCB6AC9QfCAgsQABiABBixAxiDAcICERAuGIAEGLEDGNEDGIMBGMcBwgIEEAAYA8ICCBAAGIAEGLEDwgIHEAAYgAQYCsICCxAuGIAEGLEDGIMBmAMAkgcDMC43oAfyI7IHAzAuN7gH9QfCBwUwLjUuMsgHFg&sclient=gws-wiz
    </a>
</div>
:lang(ko) {
    word-break: keep-all;
}
:lang(ko) .word-break-break-all {
    word-break: break-all; /* <= 추가 작업이 필요합니다. */
}
.container {
    width: 240px;
    padding: 1em;
    background-color: gold;
}
브라우저에서 실제 표시된 모습

caniuse.com에서 더 자세한 정보를 확인해 보세요.