There are several important questions to consider when doing your research on a new dryer. How it will vent is one of them. Depending on the configuration of your laundry room or closet, you may find that you need a good side venting option.
Standard dryer installation calls for rear venting but due to space limitations or configuration, you may need to look for a model that allows side venting. Not all models do! It's important to bring this up with your local appliance salesperson, because different brands and models have different restrictions for the options to install side venting. For example, you may only be able to side vent on one side of the dryer - most gas dryers can only be side vented to the left because of the burner housing. Dryers with "four-way venting" usually will allow you to install a side vent on either side.