These small (usually between 8-10cm), silver fish are found in various parts of the world which have warmish salt water, eg the Mediterranean. For export, they are almost always filleted, salt-cured and packed in salt or oil. Then they can be purchased in jars or tins from shops and supermarkets around the world.
In some countries, other small fish are processed in the same way. These may be called “anchovies” locally even though they could be prepared from other types of fish.
Anchovies are a great cupboard standby and are popular as a pizza topping as well as in Caesar salad and many other dishes.
These tiny fish melt away to nothing when cooked and tend to leave a salty rather than a fishy taste. They are known for imparting umami to any dish to which they’re added. For those who have not yet acquired a taste for these little beauties, capers could provide an acceptable substitute.