Most modal windows on the web take over your screen when they open. They pop up on the page and block you from viewing the content underneath until you close it.
This is sometimes useful, but sometimes it’s overkill when all you want is to give the user extra context to the content they’re viewing. At the same time, you don’t want to make the page longer to do so. If this is your case, inline modal windows are what you need.
Inline modal windows are modal windows that open inline with content without covering the page. The example above shows how an inline modal expands. Users are able to view more content without losing their page context. Clicking the X collapses the inline modal and reverts to the original state.
Had the site not used an inline modal it would’ve made the page longer and overwhelming. The content is easier to read because the user only gets more content if they expand a section.
Sometimes a modal window is what you need to keep the user focused on a task. Other sometimes an inline modal window is what you need to allow users to read your content without feeling overwhelmed.