How ASCII relates to binary
ASCII assigns a number to common characters. Binary is simply another way to write that number. For example, uppercase A is decimal 65, hexadecimal 41, and binary 01000001. That is why text-to-binary examples often show one 8-bit group for each ASCII character.
UTF-8 keeps the original ASCII values for the first 128 characters, which means basic English letters and numbers remain easy to compare. Characters outside ASCII, including emoji and many non-English scripts, may require multiple bytes in UTF-8 and can produce longer binary output.