Gravitational fields are vector fields that show forces of gravity around a large object. A gravitational field pulls all surrounding objects towards the center of mass but pulls the matter at the center of mass of the object outward.
Gravity, we know that that gravity can be a vector quantity in other words we can signify it with a vector or we can also with very large objects signify the sum of the gravity around that large object and scientists physicists sometimes talk about that as a Gravitational Field. So we take a large object like planet earth, well we know that gravity will always pull objects towards the center of the mass right? So from this direction it will pull that way, from this direction it will pull that way, from this direction and so on, so I can see I can show what looks like a gravitational field much like a magnetic field around the earth, so if we just draw all these vectors on here this is just conveying the idea that again the earth has this gravitational field around it okay since it's a vector unit, if we've got an object accelerating by earth in this direction, we can see that at any point here, let's say at this point, this vector is going to be acting on it and its going to pull in that direction okay and then this direct vector will be pulling on it, pulling it in that direction so we're going to get, we're going to get the effects of gravity pulling objects around and causing orbits and things like that because we can view gravity much like the sum of all the gravity vectors around earth as a gravitational field okay.
What happens if we go inside the earth? Is the force of gravity still pulling in this way? Well it turns out it's not, if you get to the center of earth, let's say you could dig down and get through all that magma and all that liquid rock and everything and you could survive in there at that very high temperature, what's the force pulling on an object at the center, let's say you write here the center of the earth, well now you've got actually more mass outside of you so that gravitational force is actually pulling out from the center of the object, so these gravitational fields will pull in towards the object but there at the very center they will actually pull out and that's how we can talk about gravity in terms of gravitational field.