Lossy compressors don't have the same constraints as a lossless compressor. If you data your input, compress it, and then decompress it, the output is not identical to the input. This allows the compressor to potentially compress the data far more than even the ideal lossless compressor hypothesized above.
The question mark (?), also known as the interrogation point, query, and eroteme, is a punctuation mark that indicates an interrogative clause, or phrase in many languages. The question mark is not used for indirect questions.
Anyway, here is what those check marks on messages sent via WhatsApp really mean: Single check mark â this means your message was successfully delivered to the WhatsApp server. Double check mark â this means your message was successfully delivered to the phone of your chat partner.