Pickling has two main methods: 

- lactofermentation - saltwater brine which relies on lactic acid producing backteria (lactobacillus) to create an acidic environment which is inhospitable to most bad microbes. flavors are developed by the fermentation process. 

- vinegar pickling or 'quick pickles' - uses vinegar in addition to salt in brine. Vinegar is acidic (acetic acid and water, specifically). The acidic nature of the brine means the environment is instantly less hospitable to bad microbes (thus the 'quick' in 'quick pickle') and imparts flavors along with whatever spices are included in the brine. 

Notes on Lactofermentation:
Veggies stay crunchier. Veggies last different amounts of time depending on how hard they are. 3 months for cucumbers, 7-8 months for carrots. 

2 to 3 % of the brine solution (by weight) should be salt (not table salt that's been stripped of its minerals)
e.g.: 412g of water added to your jar to submerge the food. multiply by 0.025 (aka 2.5%) and that means we add 10.3g salt to the brine solution. All fermenting solutions are acidic (pH below 4.6)

weigh down food with ceramic or glass weights (not metal). Or a ziplock bag filled with water. 

Burp daily. Refrigerate for longer shelf life.