We used to call Loader::element($element[, $arguments[, $packageHandle]])
or Loader::packageElement($element[, $packageHandle[, $arguments])
to include an element.
With Concrete CMS 5.7 and later versions, this should be written as:
// Include a core element without arguments
View::element($element);
// Include a core element with arguments
View::element($element, ['argument1' => 'value1', 'argument2' => 'value2']);
// Include a package element without arguments
View::element($element, null, $packageHandle);
// Include a package element with arguments
View::element($element, ['argument1' => 'value1', 'argument2' => 'value2'], $packageHandle);