A snippet with submitForm to redirect your form to another page and pass a variable.
With this snippet, you will be able to render a list of tags in drupal 8.
By default, users with the permission of 'administer users' cannot assign roles on the user registration form. With this snippet you can, but make sure to hide the 'administrator'-role for your users.
If you like to use the search api or a custom Views page for your search result I personally like to use the default search block and redirect it to my results page.
When creating custom blocks, sometimes you need to make sure the block is never cached f.e. when including dynamic links. 

In this case I created a custom entity called 'submenu'. In my custom module a used HOOK_LINK_ALTER to make the submenu (which contains a textfield) visible on hover. I used the code below to render my custom entity content:

In some cases you want to embed a view inside your custom module. The views_embed_view() function is the way to go. With this little snippet, you can render any view.
With this simple snippet, menu items are saved as expanded when you save your node. In some cases, this is a necessary functionality.
When using lazy loading of images, I encountered an important issue. Social sharing engines like Facebook can't read placeholder images. In this drupal 8 tutorial we'll fix this issue by creating a small custom module handling image tokens.