Top Level Transparency is an option within SOLIDWORKS that allows you to quickly view your entire model in a transparent mode. It’s like a quick-access x-ray of your model. You may need this to peer deep into the heart of your assembly. Perhaps you are trying to visually find an obscured part which is buried within your assembly. Even within an individual part, you may just want to see a particular set of features without a section view.
You don’t have to change the transparency of each and every component within your assembly or create special display state. Just turn this setting on, and then turn if off.
To turn it on, right mouse button click on the top line of your Feature Tree. Select the Top Level Transparency option from the shortcut bar or within the list of options of the right mouse button menu. Repeat to turn the mode off.
Although Top Level Transparency is a mode, it does directly affect the transparency of the assembly and components while active. This means the setting is persistent. If you turn this setting on for a component, when you open the associated assembly, that component will be transparent within the assembly. A component or assembly can also be saved with this mode active.
Besides Transparency, explore changes to Exploded Views
Another assembly tool that you may wish to explore in SOLIDWORKS might be Exploded View, which has seen a number of enhancements over the years. SOLIDWORKS 2015 introduced Radial Explode. Back in SOLIDWORKS 2013, you gained the ability to copy exploded views. More recently, you have the ability to autospace exploded components.
Each release of SOLIDOWORKS sees many enhancements for assemblies. Be sure to always review each year’s What’s New document.