What is this for?

Apple offers tools, such as Apple Configurator that allow you to create your own iOS Configuration Profiles.
Apple Configurator is only availble for MacOS devices. This is useful if you do not have access to one but still need this.

This site will help generate a configuration profile based on the network information you provide.
Using this, you can import the profile into your mobile devices (via a method such as an MDM).

You can see all of the modified output in the bottom as aqua text.

All of this is run client-side, within the browser.

Extra stuff:

Apple MDM Configuration Profile Reference
Fill out your Wi-Fi network details below. This only supports "Personal" connections.
Security
Hidden network?
Auto Join?

Generated Profile

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>PayloadContent</key>
    <array>
        <dict>
            <key>AutoJoin</key>
            <true/>
            <key>CaptiveBypass</key>
            <false/>
            <key>EncryptionType</key>
            <string>None</string>
            <key>HIDDEN_NETWORK</key>
            <false/>
            <key>IsHotspot</key>
            <false/>
            <key>Password</key>
            <string>My-Passphrase</string>
            <key>PayloadDescription</key>
            <string>Configures Wi-Fi settings</string>
            <key>PayloadDisplayName</key>
            <string>Company Wi-Fi</string>
            <key>PayloadIdentifier</key>
            <string>com.apple.wifi.managed.5A2AE473-F6B7-4D60-9778-B25D26317C41</string>
            <key>PayloadType</key>
            <string>com.apple.wifi.managed</string>
            <key>PayloadUUID</key>
            <string>5A2AE473-F6B7-4D60-9778-B25D26317C41</string>
            <key>PayloadVersion</key>
            <integer>1</integer>
            <key>ProxyType</key>
            <string>None</string>
            <key>SSID_STR</key>
            <string>Example-SSID</string>
        </dict>
    </array>
    <key>PayloadDisplayName</key>
    <string>Company Wi-Fi</string>
    <key>PayloadIdentifier</key>
    <string>WiFi-PSK-Sample.D5B78A3C-CDA8-471F-984C-06F977EF870C</string>
    <key>PayloadRemovalDisallowed</key>
    <false/>
    <key>PayloadType</key>
    <string>Configuration</string>
    <key>PayloadUUID</key>
    <string>444C9683-221C-49AF-997D-2B6B84710DAA</string>
    <key>PayloadVersion</key>
    <integer>1</integer>
</dict>
</plist>