Shipping costs are not be neglected: they can easily double the final cost of an order, and you should be very upfront about them – customers hate bad surprises.
The "Shipping" tab enables you to give some precious details about your product's package:
Package width, height, depth & weight: You should strive to fill each field, because knowing the exact size and weight of a package is not only useful to you, but PrestaShop can also direct specific sizes/weights to specific carriers automatically, based on these settings. The order's final price will appear to the customer once PrestaShop (or the customer) has selected a carrier.
These values use the default weight, volume, distance and dimension units, as set in the "Localization" page of the "International" menu.
These values do not have to be integers. If your products weight less than 1 lb., you can simply use a period (.) to indicate the fractions:
0.23 lb., etc.
Additional shipping fees. This can prove very useful to you for specific products that are particularly tricky to package, or really heavy.
Carriers. You can choose to have the current product only be shipped by a selection of carriers. If no carrier is selected then all the carriers will be available for customer orders.