Can someone please explain Salary Cap to me

My guess (cause I don't know the details of the Isle's cap situation) is that a player was just removed from LTIR and placed on the IR

No, Isles are not in LTIR. It's because of injuries the Islanders have been calling up bodies from BPT to replace. Raty/Wotherspoon/Schneider etc. Those guys eat away at the immediate cap so we aren't accruing as much every day towards the TDL. But once those guys go back down the deadline cap space will jump up significantly again. Just got to get healthy

The "accrued" cap space is a weird quirk of cap compliance being calculated daily and contracts being pro-rated -- a good explainer of it is here https://puckpedia.com/salary-cap/8-team-cap-hit-calculations-accrued-cap-space#:~:text=Cap%20space%20%E2%80%9Caccrues%E2%80%9D%20over%20time,the%20remainder%20of%20the%20year.

not too familiar with the isles, but my guess is they have had a couple injuries recently and needed to call up replacements. even though no one is on LTIR (which prohibits a team from "accruing" any more cap space), by calling up guys to fill out roster spots they are already dipping into that accrued pool, and because its pretty far away from the TDL it actually takes away a significant amount of that pool.

Easy, quick answer: look at that IR list. Each one of those guys has had a guy called up to fill his roster spot (Cory Schneider for Varlamov, Parker Wotherspoon for Pelech, Hudson Fasching for Clutterbuck, Holmstrom for Palmieri, and then Raty for Holmstrom.) Those guys have a total cap hit of $3.95M, meaning that you've added that much to the total cap hit (if you look at the Isles' CF page, you can see they've done a lot of shuffling up and down with these guys, mostly for cap purposes) which means that they're currently using $81.415M of cap space (according to CF), but with the IR guys counting against the cap, they have 27 players counting against the cap. Once guys start getting healthy and their replacements start filtering back down to Bridgeport, you'll see the cap change accordingly.

The reason it fluctuates so much is that in the NHL, cap is calculated at end of business every day - that's why you see guys like Fasching & Holmstrom "sent" up & down a few times on paper over the past week, based on when games are being played - each day that they're "in the AHL", they don't count against the NHL cap and the Islanders bank a few extra dollars.

Got it thank you very much. Honestly, these young kids look fast and seem to be what's missing for the Islanders. It is going to be interesting once everyone comes back, but Fasching seems like he needs to be in the lineup every night. Cizikas, Pageau and Parise line seems like a much more rejuvenated and better offensive line than the martin clutterbuck and cizikas line is now. I like Raty as center number 4. Wotherspoon has looked very good as well, but hard to imagine he sticks when pelech comes back eventually.