When it comes to child custody, some people tend to think of the topic as an all-encompassing umbrella. If one parent is awarded child custody, then that's it. The other parent is either out of luck or they don't get to spend much time with their child. This, however, is a false interpretation that in some ways is propagated by dramatic TV shows and films.
In reality, there are four forms of child custody: two that relate to decision making and residence, and two that relate to which parent controls those factors.
To elaborate on that, consider the first two forms of child custody: physical custody and legal custody. Physical custody relates to the residence that the child lives at. Legal custody, meanwhile, relates to the legal authority to make decisions on behalf of the child. So, where does the child go to school? What religion does he or she practice? What about healthcare? The parent with legal custody gets to make these decisions.
Now, the other two forms of custody are joint custody and sole custody. If you agree to joint custody, then that means both parents share the responsibilities at hand. Sole custody means that only one parent has the responsibility.
No matter what your arrangement is, it is likely that it will change over time. Your child will grow and change, just as your relationship with your ex-spouse will change. Indeed, your life will change: new jobs, new living arrangements, new significant others. All of this will lead to the need to alter your child custody arrangement.