What does lossless compression mean?

Lossless compression refers to a method of reducing the size of a file without any loss of information. This means when a file is compressed using a lossless algorithm, every single bit of data that was originally in the file remains intact and can be perfectly reconstructed when the file is decompressed. This is crucial in scenarios such as text files or certain image formats (like PNG), where even slight alterations in data could lead to significant losses in quality or information.

Unlike other methods of compression, lossless compression does not discard any data (which is what the second choice implies), and it maintains the integrity of the original content completely. This is why lossless compression is particularly important for applications where fidelity is paramount, such as in software programs, documents, or certain types of image and audio files where any degree of loss would be detrimental.

In terms of the context provided by the other options, the first choice about file size remaining unchanged is incorrect because lossless compression indeed reduces file size. The option about data being removed to save space reflects lossy compression techniques, where some data is discarded; thus, it doesn't apply to lossless methods. Lastly, the idea that only essential data is retained implies that some information is discarded, which contradicts the fundamental