Supermarkets Are Everywhere In Germany
How many grocery stores do you have in your city or town? If it's a bigger city, the answer may be "who knows?", but in a small town, it's probably only one. In Germany, the answer its "one on approximately every second street corner." It sounds like an exaggeration, but for an American who travels through Germany for any amount of time, whether they visit the downtown areas or go through the residential parts of a given city, the number of grocery stores is likely to be surprisingly high.
In Germany, grocery shopping (einkaufen) was historically a daily or near daily occurrence. Apartments and refrigerators are often on the smaller size, and buying in bulk is much harder when most people don't travel with a car on a regular basis, and a substantially smaller part of the population even owns a vehicle larger than a bicycle. As such, it is much easier to sustain a larger number of grocery stores (Supermarkt).
The grocery stores over here are usually much smaller than those in the U.S., typically falling much closer to the size that an American might expect to see from one of the chain pharmacies in the U.S. than the giant grocery stores we are used to. In general, this means that there are fewer options in any given store for a particular product, particularly in discount grocery stores like Aldi. If you are looking for specialty items, you'll have to make a plan of going to larger shops, or visit more expensive grocery stores.
If you want to make the best use of the many types and sizes of grocery stores in Germany, check out all of the ones around you soon after you first move in. You'll soon find out which shop has the best deal on what you like to get, and where to go if you need a specific product. If you prefer to shop once a week like you probably would in the U.S., you may find yourself shopping more frequently; maybe not every single day, but instead buying for a few days at a time from a given shop.
Should you be hunting for a certain product that you like to get in the U.S., you may have to do some research or exploring to find it. Often times I've been looking for a product, only to find out that the same or similar thing is packaged substantially different in Germany than I was used to in the U.S.. Additionally, not all products appear with the same frequency in Germany as they do in the U.S. (for me, spicy foods fall into this category). In the last few years that I've been living in Germany, the number of actual American products which have become available over here has significantly increased (Mountain Dew and Doritos were huge steps forward), but I still find that there are certain things it's better to just make from scratch (like salsa).