There are three ways to preview Prototypes — in the Mac app, on your iOS device using Mirror, or in the web app where you can share prototypes with others.
How to preview a Prototype in the Mac App
To start a preview in the Mac app, click the Preview 
button in the toolbar. If you’ve set a Start Point, your Prototype will start from there. If not, it’ll start from the currently selected Artboard.
- Click anywhere within the Preview window to see tap targets that show you where Links and Hotspots are on the current Artboard.
- The back button will take you back a step to the previous Artboard in your prototype.
- The Artboards drop-down menu gives you a quick way to jump between different Artboards.
- The flag icon
sets the Artboard you’re currently viewing as a Start Point.
How to preview a Prototype in the web app
When you open a document in the web app, you’ll see any Prototypes it contains in a section at the top of the document overview. Click on a Prototype’s thumbnail to open and preview it in your browser.
Like the Preview window in the Mac app, clicking anywhere on the screen will highlight any Hotspots 
or Links. To go back a step to the previous Artboard 
, click the back button in your browser.
If you’ve enabled comments on your document, anyone viewing your Prototype can choose View Artboard at the bottom of the window to leave the Prototype and enter a static view of that Artboard . From there, they can leave comments in the sidebar. To close the Prototype and return to the document overview, choose Close.
How to View Prototypes without Hotspots
To share a Prototype preview without hotspots enabled, hover over the Prototype thumbnail in the documents overview, click on the … button and choose Copy link to Prototype with Hotspots disabled.
How to Preview a Prototype in Mirror
Launch the Sketch Mirror app on your iOS device and connect via USB or Wi-Fi, then click the notifications bell 
.
In Mirror, tap on an Artboard to start previewing your Prototype. From there, you can tap on Links and Hotspots to navigate your Prototype, or swipe down on an Artboard to close it.