Here are some common applications that typically use 16 gauge staples:
Hanging drywall
Stapling drywall to ceiling and wall framing members.
Roofing underlayment
Securing roofing felt, ice & water shield or synthetic underlayment.
Installing house wrap
Attaching house wrap or rain screen materials to sheathing.
Installing wood siding/trim
Securing pine, cedar, vinyl or fiber cement siding/corner boards.
Flooring installation
Attaching most types of flooring such as laminate, hardwood, tile.
Attaching vapor barriers
Stapling basement/crawl space vapor barriers to joists.
Attaching decking boards
Securing composite, pressure treated or cedar deck boards.
Installing window/door trim
Attaching jamb extensions, casings and other trimwork.
Furniture assembly
Building cabinets, tables, chairs, bookcases and other wood pieces.
Upholstery projects
Stapling fabric, vinyl or leather to furniture frames and pads.
So in summary, 16 gauge staples work well for many indoor/outdoor construction and remodel projects.