An application is filed, containing a description of the patented subject matter, one or more drawings, and one or more legal descriptions of the patented subject matter called claims. Once the patent is filed, you get a filing date, meaning that you have priority over any other patent filed after that date with the same claimed subject matter.
Sometime in the future, usually between 6 months and 3 years, you will get a response from the patent office. Usually this response could be an office action. An office action lists all of the problems that the examiner found with this patent application, called objections and rejections. These issues could be with the wording of the application or claims themselves, but more likely it is with the application in counterpoint with earlier applications as explained on https://inspirationfeed.com/inventhelp/.
The arguments that the examiner usually uses deal with obviousness and lack of novelty. Other grounds would be proof that the invention was in use prior to 12 months before the patent was filed or offered for sale in the US more than 12 months prior to filing. There are others, but the usual arguments made by the examiners deal with obviousness and novelty.
Obviousness means that the examiner would argue that, in light of one or more earlier applications, it would have been “obvious” to someone skilled in building things similar to your subject matter (“skilled in the art”) to make what you have invented. Lack of novelty means that the elements of your claim can be found in one or more prior patents; not in combination, but in each one. The idea of combining multiple references is obviousness not novelty as you can see from https://southfloridareporter.com/how-inventhelp-can-assist-with-new-invention-ideas/.