Clarify WPT on home page table

I'm looking at https://webstatus.dev/ , and I see a table with these column headers: Feature, Baseline, Availability, and WPT.

I do not know what WPT stands for or what it means. I'm guessing "Web Platform Something". The values are percentages. Does this indicate the amount of support that browsers offer for this feature? How does this differ from the information in the column labelled "Availability"? Maybe, it would be good to provide a tooltip or to expand the column header to the unabbreviated title.

I'm a web developer that is subscribed to Google's email newsletters to developers. That is how I discovered this website. I wanted to give some feedback on the usability of the website. The wiki documentation is currently empty. I know I could probably work out the meaning of WPT by reading through multiple GitHub issues, but I thought you might appreciate the feedback from a first-time visitor. The website looks great, thank you for making it and sharing it!