Layers.
PDF is an absurdly complex file format. It's part of the reason there is no single "good" PDF reader, just a lot of mediocre PDF readers that are all terrible in their own way. Which is a topic for another day.
There are several ways to remove data in a PDF:
- Remove the data. This is much harder than it sounds. Many PDF tools won't let you change the content of a PDF, not because it isn't possible, but because you'll likely massively screw up the formatting, and the tools don't want to deal with that.
- Replace the data. This what what all the "blackout" tools do, find "A" and replace with "🮋". This is effective and doesn't break formatting since it's a 1-to-1 replacement. The problem with "replacing" is that not every PDF tool works the same way, and some, instead, just change the foreground and background color to black; it looks nearly the same, but the power of copy-and-paste still functions.
- Then you have the computer illiterate, who think changing the foreground and background color to black is good enough anyway.
PDF is an absurdly complex file format. It's part of the reason there is no single "good" PDF reader, just a lot of mediocre PDF readers that are all terrible in their own way. Which is a topic for another day.
There are several ways to remove data in a PDF:
- Remove the data. This is much harder than it sounds. Many PDF tools won't let you change the content of a PDF, not because it isn't possible, but because you'll likely massively screw up the formatting, and the tools don't want to deal with that.
- Replace the data. This what what all the "blackout" tools do, find "A" and replace with "🮋". This is effective and doesn't break formatting since it's a 1-to-1 replacement. The problem with "replacing" is that not every PDF tool works the same way, and some, instead, just change the foreground and background color to black; it looks nearly the same, but the power of copy-and-paste still functions.
- Then you have the computer illiterate, who think changing the foreground and background color to black is good enough anyway.