Every method targets the same enemy — microbial growth — through different chemistry:

• Salt pulls water out of cells through osmosis, dehydrating bacteria until they die or go dormant
• Sugar works the same way — jam and honey preserve fruit by creating water activity too low for microbes
• Vinegar (acetic acid) drops pH below the survival threshold of most bacteria
• Smoking coats food in phenols and organic acids from burning wood, which slow microbes and oxidation
• Pressure canning heats low-acid food to about 116-121°C, high enough to kill dangerous Clostridium botulinum spores when time and pressure are controlled