Main Structure

The form-group class has been removed in Bootstrap 5.
Now, a form control unit is consisted of 3 main elements placed inside any div or container:

form
  div`mb-3`
    label`form-label`
    input`form-control` or `form-select`
    p`form-text`

  button`.btn.btn-primary`

Label Possible Attributes

class=form-label, for,

Input Possible Attributes

class=form-control, id, type, value, placeholder, disabled, readonly, aria-label, aria-describedby

Form Text Attributes

class=form-text, id

Checkboxes

  div`form-check` [`form-check-inline`]
    input`form-check-input` 
    label`form-check-label`

Inline Form

div`row g-3 align-items-center`
  div`col-auto`
    label`col-form-label`
  div`col-auto`
    input`form-control`
  div`col-auto`
    span`form-text`

Disable A Form

<form>
  <fieldset disabled>
    <legend>Disabled fieldset example</legend>
    <div> ... </div>
  </fieldset>
</form>