The <group> element is Odoo's main element, which is used for organizing content. Fields placed within a <group> element are rendered with their title, and all fields within the same group are aligned so that there's also a visual indicator that they belong together. You can also nest <group> elements; this causes Odoo to render the contained fields in adjacent columns.

In general, you should use the <group> mechanism to display all of your fields in the from view and only revert to the other elements, like <notebook>, <label>, <newline>, and more when necessary.

If you assign the string attribute on a group, its content will be rendered as a heading for the group.

You should develop the habit of assigning a name to every logical group of fields, too. This name is not visible to the user, but is very helpful when we override views in the following recipes. Keep the name unique within the form definition to avoid confusion about which group you refer to. Don't use the string attribute for this, because the value of the string will change eventually because of translations.