HO train track question?

Could someone in detail explain to me what the some of the differences are in model HO track as far as connectivity goes? Meaning would atlas track work with another brand and so forth? Do any brands interchange with each other? If I buy a particular brand do I need to stick with that brand? Also any recommendations on a particular track to go with would be helpful as well. I am just starting out, but looking to slowly build up. Any information will be helpful. Thanks.