How to create System.xml configuration in Magento 2?

Today, we are going to see how to create system.xml, step-by-step.

Step 1: Create System.xml

We can do it by creating a system.xml file in the
app/code/MageMonkeys/HelloWorld/etc/adminhtml/
directory.

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Config:etc/system_file.xsd">
    <system>
        <tab id="magemonkeys" translate="label" sortOrder="10">
            <label>MageMonkeys</label>
        </tab>
        <section id="helloworld" translate="label" sortOrder="130" showInDefault="1" showInWebsite="1" showInStore="1">
            <class>separator-top</class>
            <label>Hello World</label>
            <tab>magemonkeys</tab>
            <resource>MageMonkeys_HelloWorld::helloworld_config</resource>
            <group id="general" translate="label" type="text" sortOrder="10" showInDefault="1" showInWebsite="0" showInStore="0">
                <label>General Configuration</label>
                <field id="enable" translate="label" type="select" sortOrder="1" showInDefault="1" showInWebsite="0" showInStore="0">
                    <label>Module Enable</label>
                    <source_model>MagentoConfigModelConfigSourceYesno</source_model>
                </field>
                <field id="display_text" translate="label" type="text" sortOrder="1" showInDefault="1" showInWebsite="0" showInStore="0">
                    <label>Display Text</label>
                    <comment>This text will display on the frontend.</comment>
                </field>
            </group>
        </section>
    </system>
</config

Step 2: Set default value

We can do it by creating a config.xml file in the
app/code/MageMonkeys/HelloWorld/etc/ directory.

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Store:etc/config.xsd">
    <default>
        <helloworld>
            <general>
                <enable>1</enable>
                <display_text>Hello World</display_text>
            </general>
        </helloworld>
    </default>
</config>