You may regret asking, but sure!
Conditional formatting refers to telling the cells “when this thing is in the box, make it look different.” This difference could be text color, cell color, font, text size, bold/underline/italic, whatever. In the case of my sheet, when you put a check mark in the box, the text changes to black and the cell color turns blue. When a period is in the box, the text turns white (so it looks like nothing is there- important for later, stay with me).
This isn’t all that hard to figure out necessarily, but it does require extra detail and makes updating the sheet so much smoother when you don’t have to change cell settings every time.
I also have all of the cell in my sheet auto-count themselves based on a period (cards I don’t have) or a check mark (cards I do have), which is displayed as a bar graph and percentage on my main page. This requires a little more knowledge of formulas and how everything works together.
Finally, data from my main pages is linked to my supplementary pages. The main pages have everything sorted chronologically by set, but since that’s a little hard to parse when I don’t know what illustration I’m looking for, I created supplemental pages with cards organized by illustration. Linking the data allows me to check a box on my main sheet, and it will auto-update on my supplemental pages, giving it a check as well. These are also conditionally formatted.
My guide: How I Made My Collection Tracker (and you can too!): An In-Depth Guide may explain that in more detail, but you did ask for brief, so I tried my best, haha.