MSR 100 Wing, the lightest "tent"
The lightest tent I know of is a tarp. The MSR wing can be combined with a bug net when needed, as in the MSR Thru Hiker. As a separate tent one needs a footprint to keep the sleeping bag off the dirt, which on a recent hike I used painter’s drop cloth (thin plastic) as a footprint. The photo below shows rocks holding the edges of the footprint down. Since then I have put grommets in the corners, so the footprint can be staked down.
I love the ability to see outside the tent, added ventilation, and of course the light weight. Hiking poles are used to support the ridgeline, and the tips of the hiking poles fit in a grommet on the tarp. A disadvantage is that the tarp is surrounded by guy lines, so everyone including me trips on the guy lines. I did a major face plant on the guy line, and found myself in the dirt hard. I think I’ll put orange strips in the middle of the guy lines, for visibility. I’ve seen this tarp on Amazon for $130, pricey but probably worth it. Other tarps are available cheaper.