German soft pretzels, or Brezeln, are a well recognized and popular food item with a long history and an interesting connection to chemistry. Around 610 AD, the pretzel was first made by monks in Northern Italy or Southern France. This was then supposedly used to reward children for reciting their prayers correctly, which corresponds to the shape; the pretzel’s shape represents how people at that time prayed, with arms crossed across their chests, and hands on opposite shoulders. Even the name, pretzel (or Bretzel) appears to be derived from the Latin word for “little arms” (bracellae) or the Italian word for “little rewards” (pretiolas). However, it is unlikely that these early pretzels were similar in colour or taste to the iconic modern day Bavarian pretzel.
In 1839, Anton Nepomuk Pfanenbrenner accidentally brushed lye, instead of a sugar solution, onto a batch of pretzels. He decided to bake them anyway, and the resultant pretzel had a unique colour and flavour. Crust colour and flavour are results of the Maillard reaction, a reaction between reducing sugars and amino acids, both of which are present in bread in the form of the components of sucrose (fructose and glucose) and gluten. What made Pfanenbrenner’s accident so unique was that, although unknown at the time, basic substances (high pH) significantly decrease the time that it takes for the Maillard reaction to proceed  . Since the sodium hydroxide (lye) is in low concentration and is rendered harmless through the baking process, there are no negative effects to consuming prezels dipped in strong bases to increase the rate of the Maillard reaction. (Some other factors known to increase the rate of the Maillard reaction are adding reducing sugars or proteins, or increasing the bake temperature.)
Variations in pretzels include shape, formula, and finishing. There are regional differences in shaping and formulation, for instance, pretzels from Bayern (Bavaria) having much thicker ‘arms’ and any exposure of the white interior is through rips in the crust. The fat content of these pretzels is limited to 3%, compared to anywhere as high as 10% fat content for Schwaebische (Swabian) pretzels, which also have much thinner arms, and are typically scored along the thicker ‘body’ of the pretzel.
On various holidays and events throughout the year, pretzels may be baked with a sweet dough or puff pastry and brushed in a sugar solution, or simply dipped in boiling water instead of a dilute base; or, for Oktoberfest, pretzels many sizes larger than the usual may be baked .
To make traditional German pretzels: http://www.npr.org/sections/thesalt/2014/08/09/338591194/for-a-proper-pretzel-crust-count-on-chemistry-and-memories
And a tutorial on how to shape them: https://www.youtube.com/watch?v=GVXLCUnWHMg