Here is one concept of objectivity, taken from SEP.
Let's take objective properties to be qualities of an object that exist independently of a perception of that object; for example, the primality of the number 7, or the atomic mass of hydrogen. The intuition being that these facts would remain even if there was no one around to perceive them.
In The View from Nowhere Thomas Nagel identifies three steps to identifying such objective properties.
First we must recognise that our perceptions are caused by causal processes (light reflecting off objects into our eyes and sounds hitting our eardrums etc.) and the effects those processes have on our sense organs and brains.
Second we must consider that these causal processes also act on other things (than ourselves) and sometimes never act on anything at all. Think of a tree falling in the woods with no one around to hear, it intuitively seems that something must happen in that situation and that something must be detachable from a human perspective.
Finally we must form a conception of an entity's nature that is detached from our perspective, hence the title of the book, The View From Nowhere. Only by abstracting out our perspectival experience of the object are we able to gain a sense of objectivity.