Fields, panels and the editing screen
Every field type, where each one lands on the screen, and how repeaters and blocks work.
There are eleven field types: text, textarea, markdown, url, number, select, toggle, media, color, list and blocks. Most are what you would expect; three are worth a note.
markdown
With 'editor' => true the field takes the main column and gets the full editor —
toolbar, Write and Preview tabs, a word count, a reading-time estimate, and a button
that inserts an image from the media library.
list
A repeater. Declare the sub-fields and an editor gets rows they can drag to reorder:
['name' => 'links', 'type' => 'list', 'item_label' => 'label', 'fields' => [
['name' => 'label', 'type' => 'text', 'label' => 'Label'],
['name' => 'url', 'type' => 'url', 'label' => 'URL'],
]],blocks
The same idea with several kinds of row, which is how you build a page out of
sections. The home page of this site is one blocks field with eight sections in it.
Each block type you declare gets one small template, and the editor can add, reorder,
hide, duplicate and delete them — but never invent a new one.
A note on help text
Every field takes a help line. Write them. One plain sentence saying what belongs in
the field and where it will appear is the difference between a panel a client trusts
and one they guess at.