<SEC-DOCUMENT>0001057352-21-000042.txt : 20210302
<SEC-HEADER>0001057352-21-000042.hdr.sgml : 20210302
<ACCEPTANCE-DATETIME>20210302162722
ACCESSION NUMBER:		0001057352-21-000042
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20210228
FILED AS OF DATE:		20210302
DATE AS OF CHANGE:		20210302

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Ruggles Lisa
		CENTRAL INDEX KEY:			0001717178

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-24531
		FILM NUMBER:		21704039

	MAIL ADDRESS:	
		STREET 1:		C/O COSTAR GROUP, INC.
		STREET 2:		1331 L STREET NW
		CITY:			WASHINGTON
		STATE:			DC
		ZIP:			20005

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			COSTAR GROUP, INC.
		CENTRAL INDEX KEY:			0001057352
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-BUSINESS SERVICES, NEC [7389]
		IRS NUMBER:				522091509
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1331 L STREET, NW
		CITY:			WASHINGTON
		STATE:			DC
		ZIP:			20005
		BUSINESS PHONE:		2023466500

	MAIL ADDRESS:	
		STREET 1:		1331 L STREET, NW
		CITY:			WASHINGTON
		STATE:			DC
		ZIP:			20005

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	COSTAR GROUP INC
		DATE OF NAME CHANGE:	19990805
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_161472042832677.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2021-02-28</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001057352</issuerCik>
        <issuerName>COSTAR GROUP, INC.</issuerName>
        <issuerTradingSymbol>CSGP</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001717178</rptOwnerCik>
            <rptOwnerName>Ruggles Lisa</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O COSTAR GROUP, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>1331 L STREET, NW</rptOwnerStreet2>
            <rptOwnerCity>WASHINGTON</rptOwnerCity>
            <rptOwnerState>DC</rptOwnerState>
            <rptOwnerZipCode>20005</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Senior VP, Global Research</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.01 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2021-02-28</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>180</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>17513</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.01 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2021-02-28</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1388</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>823.76</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>16125</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Shares forfeited from February 28, 2018 performance restricted stock grant after measurement and certification of actual achievement of the performance goal by the Compensation Committee.</footnote>
        <footnote id="F2">Represents all shares of Common Stock owned, consisting of 1,397 shares of Common Stock and 15,398 shares of Common Stock subject to unvested Restricted Stock grants, 359 shares of Deferred Stock Units and 359 shares of unvested Restricted Stock Units.</footnote>
        <footnote id="F3">Represents all shares of Common Stock owned, consisting of 3,089 shares of Common Stock and 12,318 shares of Common Stock subject to unvested Restricted Stock grants, 359 shares of Deferred Stock Units and 359 shares of unvested Restricted Stock Units.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Jeannette Koonce, Attorney-in-Fact</signatureName>
        <signatureDate>2021-03-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
