A motion to compel asks the court to order either the opposing party or a third party to take some action. This sort of motion most commonly deals with discovery disputes, when a party who has propounded discovery to either the opposing party or a third party believes that the discovery responses are insufficient. The motion to compel is used to ask the court to order the non-complying party to produce the documentation or information requested, and/or to sanction the non-complying party for their failure to comply with the discovery requests. - https://en.wikipedia.org/wiki/Motion_to_compel

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Discovery, in the law of the United States and other countries, is a pre-trial procedure in a lawsuit in which each party, through the law of civil procedure, can obtain evidence from the other party or parties by means of discovery devices such as a request for answers to interrogatories, request for production of documents, request for admissions and depositions. Discovery can be obtained from non-parties using subpoenas. When a discovery request is objected to, the requesting party may seek the assistance of the court by filing a motion to compel discovery. - https://en.wikipedia.org/wiki/Discovery_(law)#

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The two types of motions to compel discovery

Although the rules of civil procedure don’t differentiate them, there are really two distinct types of motions to compel discovery: one addressing the untimeliness of the response and one addressing the inadequacy of the response. Each type requires a very different strategy to prosecute. - http://www.gregoryforman.com/blog/2014/03/the-two-types-of-m...