Archive formats do two things: bundle multiple files into one, and compress them to save space. Some do both (ZIP), some just bundle (TAR), and some just compress (GZIP). The format wars are largely over — ZIP won for consumers, TAR.GZ won for developers — but you'll still encounter RAR files from people who downloaded WinRAR in 2004 and never looked back.
The main differences are compression ratio and compatibility. 7Z compresses tightest but requires third-party software. RAR compresses well and adds recovery records. ZIP compresses least efficiently but opens natively on every operating system. For most people, that universal compatibility trumps a 15% size difference.
Security note: archive files from unknown sources are a common malware delivery method. The archive itself isn't dangerous — it's what's inside. Always scan extracted contents before running any executables, and be suspicious of password-protected archives from unknown senders (the password prevents your antivirus from scanning the contents).
Archive files from unknown sources may contain malware. Scan contents before extracting.
Archive format. Contents could include drivers or system files — only extract CAB files from trusted sources.
JAR files contain executable Java code. Only run JARs from trusted sources. Verify digital signatures when available.
RAR files from unknown sources may contain malware. Scan contents before extracting.
Archive that may contain any files. Extract and inspect contents before running anything.
Contains executable Java web application code. Only deploy WARs from trusted sources.
ZIP files from unknown sources may contain malware. Scan contents before extracting.