We should use the self-closing format when there's no content in our single-file components, unless they are used in a DOM template. For example, these are considered bad practice:
// .vue
<PostItem></PostItem>
// .html
<post-item/>
They should be written as follows:
// .vue
<PostItem/>
// .html
<post-item></post-item>
These are only a few essential rules. There are more, such as rules for writing multi-attribute elements, directive shorthands, quoted attribute values, and so on. But the selected rules that we've highlighted here should be enough for you to complete this book. You can find the other rules and the full style guide at https://vuejs.org/v2/style-guide/.
