Pack weight can be a userful measurement and/or proxy for how comfortable a load is to carry, how efficient your gear selection, what "category" of hiker you are (Tradition, LW, UL, SUL), and possibly several other things. Several years ago, you heard a lot about minimizing pack weight on the BPL forums. It seems we have all matured some since, and now it's more about simplicity and enjoying the experience - both of which many folks here would argue is enhanced by a light load.
In any event, measure or compare what works for you. But here's some loosely defined terminology and references...
I track my 'base weight' which includes that will be in my pack for a majority of the trip, excluding those items that are to be consumed along the way. So for example, raingear is in my base weight, but my hat and trekking poles are not. My sleeping bag is in my base weight, but my pocket knife is not. Base weight is useful as a reference for comparing across different trips and seasons. This is also probably the most commonly referenced 'pack weight' around here. I think you'll find UL defined here as a base weight under 10 lbs, but it really shouldn't matter to anyone other than to you as a frame of reference. My own base weights range from 8 to 15 lbs depending on location and season.
I also calculate my 'consumables' weight, which is food, water, sunscreen, TP, etc. For me the only big variable there is trip duration, so this is primarily a calculation to get to total pack weight. Far more useful is to look at consumables in terms of optimization - maximizing calories/ounce in my food to minimize weight, for example.
My total pack weight is everything in or on my pack. It does NOT include those items I wear or carry a majority of the trip. So still no trekking poles! Total pack weight is the true measure of pack comfort, but it varies continuously along the route as food is consumed and water is drank or refilled, so most people hate to quote an exact number. I personally prefer to keep this number below 25 to 30 lbs at all times, and to average more like 20 lbs or less.
People also measure 'skin-out' weight, which is said to include everything you weren't born with. Frankly, I couldn't care less. I mean, really, who cares what my socks weigh (64.7 grams by the way)!?!