This tool inserts the Unicode combining long solidus overlay (U+0338) — a diagonal slash mark meant to be drawn through the character right before it — after every letter in your text, which is the same trick used to render symbols like ∉ ("not an element of") by slashing through ∈. Because it's a combining mark rather than a new letter, most fonts draw it directly on top of the preceding character, producing a crossed-out or 'redacted stamp' look while the underlying text stays fully intact and selectable. Rendering quality varies by font: some fonts center the slash nicely over narrow letters but let it drift on wide ones, and a few very old renderers may show the slash as a separate mark next to the letter instead of overlapping it.
No — the original letters are untouched; a separate Unicode combining mark (the long solidus overlay) is inserted after each one, and fonts draw that mark directly over the preceding character to create the visual slash.
Combining marks are positioned by the font's own rendering rules, and since fonts are tuned mainly for accents rather than a full-width overlay slash, the alignment can look slightly different on wide letters versus narrow ones.
Yes — because the base letters are unmodified, most search functions that don't specifically account for combining marks will still find the underlying word, though some strict searches may treat the slashed text as a different string.