What is charge ??

All matters are made by molecules and all molecules made by atoms. And we know very well on based of physics theories all atoms are formed by electron , proton and nuetron. 

We can devide atoms have mainly in two parts :

First Nucleus and second, electrons rotating around the nucleus, proton and nuetron have part of nucleus and a other particle which knows as electron rotation around the nucleus. 

Proton have positive charged and electron have negetive charged.

Charge is the fundamental and Physical properties of Matter . A charge emitt  or absorb field lines . Positive charge always emmit electric field lines and a negetive charge absorb electric field lines . When a charge particle placed in a electric field then it will fill a force , this force can be attractive and negetive 

When in a positive charge particle filed we put a negative charge particle then both are attract to each other. Both charge patricle have same nature then it will repulsive each other . So charge is fundamental property of Matter.