DIL is an acronym for “Dual In Line” chips/packages including IC’s, connectors, and Resistor Nets. Dual In Line literally means two sets of in-line pins. These packages normally have a notch indicating which end has pin one, and some have a small dot by pin 1.

More complex systems like CPU’s now use Pin Grid Arrays as they need more density so they can get more connections into a smaller space - although with new fast in-circuit serial protocols, expect this to change and to see new interesting low-pin-count packages too.