A custom module is a reusable block you write yourself, in HTML with optional CSS and JavaScript. Once saved it becomes a Custom Module element you can drop onto any page in the builder, as many times as you like — edit the module once and every page using it updates.
Creating one
Go to Custom Modules in the sidebar. Each module has a name, a description, and its HTML, CSS and JS. There's a starter library of ready-made modules to browse and adapt, with a live preview.
Data sources
A module can optionally be fed live data from your site. Choose a data source of Gigs or Projects and your markup gets that content to render however you want — a custom tour-date layout, or a portfolio grid that doesn't look like the built-in one. Leave it on None for a purely static block.
When to reach for one
Most things are quicker with the standard elements. Custom modules earn their place when you need a specific layout the built-in blocks don't offer, or when you want the same hand-built block in several places without maintaining copies.
A caution
Custom modules run on your public site exactly as written, so a broken tag or a JavaScript error will show up for visitors. Preview before you publish, and keep third-party embeds to sources you trust.