ASCII Converter

ASCII is a 7-bit encoding standardised in 1963: 128 code points, of which the first 33 are control characters that were originally instructions to a teleprinter rather than anything printable. Code 7 rang a physical bell. Code 13 returned the carriage to the left margin and code 10 advanced the paper by one line, which is why Windows still ends a line with both and Unix with only the second. When you convert text here and see numbers below 32 appear, those are what you are looking at, not characters that failed to display, but instructions that were never meant to be shown.

The printable range runs from 32 (space) to 126 (tilde), and the layout inside it is deliberate rather than arbitrary. Digits start at 48, so subtracting 48 from a digit's code gives its value: the trick every introductory parsing exercise relies on. Uppercase A is 65 and lowercase a is 97, exactly 32 apart, which means the difference between cases is a single bit. Flipping bit 5 changes case, and that is the actual mechanism behind the case-conversion routines in most low-level code.

Everything above 127 is where ASCII ends and the trouble begins. For decades each vendor filled the upper 128 slots differently (Latin-1, Windows-1252, dozens of regional code pages) which is why a document written in one and read in another turns accented letters into garbage. Unicode resolved this by defining a single code point for every character, and UTF-8 encodes those code points so that the first 128 are byte-identical to ASCII. That backwards compatibility is the reason ASCII still matters: valid ASCII is valid UTF-8, and always will be. For anything outside the 128, use the Unicode converter, which reports code points rather than pretending a byte value is a character.