Question

Why would <textarea col="5" row="5" /> break my layout in my modern browser but not if I explicitly use a closing tag such as <textarea col="5" row="5" /></textarea>?
This has been bothering me. Is it part of the standard somehow?

Answer 1

Yes, it is part of the standard:

http://www.w3.org/TR/html401/interact/forms.html#h-17.7

17.7 The TEXTAREA element

<!ELEMENT TEXTAREA - - (#PCDATA)       -- multi-line text field -->
<!ATTLIST TEXTAREA
  %attrs;                              -- %coreattrs, %i18n, %events --
  name        CDATA          #IMPLIED
  rows        NUMBER         #REQUIRED
  cols        NUMBER         #REQUIRED
  disabled    (disabled)     #IMPLIED  -- unavailable in this context --
  readonly    (readonly)     #IMPLIED
  tabindex    NUMBER         #IMPLIED  -- position in tabbing order --
  accesskey   %Character;    #IMPLIED  -- accessibility key character --
  onfocus     %Script;       #IMPLIED  -- the element got the focus --
  onblur      %Script;       #IMPLIED  -- the element lost the focus --
  onselect    %Script;       #IMPLIED  -- some text was selected --
  onchange    %Script;       #IMPLIED  -- the element value was changed --
  >

Start tag: required, End tag: required

Why it breaks is another different story altogether, browsers could also implement it such that it just creates an empty textarea and not break. But since this is required by the standard, you should just follow it.

— EDIT —

Also as per @Seth comment (thanks!), it doesn’t have value attribute, so initial values go inside the tags.