You must allow your PS4 and Vita to link up first, however. Go into your PlayStation 4's Add Device screen to find a temporary code that you can input on your PS Vita device. This will grant access across the two platforms, allowing you to instantly peruse the Remote feature. This is a one-time ordeal, which will never have to be done again between the two specific pieces of hardware.
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Syncing the two devices requires a sturdy WiFi connection, but is seamless. Once synced, users can control PS4 games with their Vita, playing using the small screen. Controller options will reset upon the switch back and forth, so diving into the Options screen of the game you're playing may be required.
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Connecting to the PS4 can be done while the PS4 is on or while on StandBy mode.

Remote Play has a limited but undefined range. This feature is optimal when both the PlayStation 4 and the PS Vita are located within the confinements of the same WiFi network at the time of gameplay. Taking the Vita outside of the range of your network (on a different Wi-Fi) is possible and optimal with a PS4 wired connected to good internet speed and good Wi-Fi speed on vita. For exemple 15 mbit/s download and 10 mbit/s upload on both connection will make remote play work with really low latency. But using remote play outside of your network might result in connectivity problems, or latency, if some of the above are not respected. 3G will not support Remote Play, but it is possible to create a hotspot on a LTE enabled smartphone to make it work.