Content types are groups of common fields and their data, as well as options like show article title or date, send an email on submission, etc. Out of the box, Joomla has a limited number of content types. SEBLOD lets you extend Joomla’s core content types like Article, Category and User and/or create your own.
For example, you might have one content type for a blog posting with a title field, date, author, intro/full text, blog image. So far that’s pretty similar to what standard Joomla offers. But maybe as the admin you could hide many of the options that the person adding the blog post doesn’t need or should have access to such as category (you could assign a default), show title, show created date, etc. SEBLOD allows you to completely customize you forms exactly the way you want!
You could also create custom fields for your content types that are individually searchable, easy to fill in, and themable. A product for example could have fields for a title, description, image gallery, price, color, size, weight, etc. or a testimonial type could have fields for name, company, phone number, years known and testimonial text.