Combinators (, >, ~, +, ,)

CSS Tricks

/* Descendant */
header h1 {
  /* Selects all Heading 1 elements in a Header element. */
}

/* Child */
header > h1 {
  /* Selects all Heading 1 elements that are children of Header elements. */
}

/* General sibling */
h1 ~ p {
  /* Selects a Paragraph as long as it follows a Heading 1. */
}

/* Adjacent sibling */
h1 + p {
  /* Selects a Paragraph if it immediately follows a Heading 1 */
}

/* Chained */
h1,
p {
  /* Selects both elements. */
}