breadboard in electronics

A breadboard (solderless breadboard, plugboard) is a reusable solderless device used to build a (generally temporary) prototype of an electronic circuit and for experimenting with circuit designs. This is in contrast to stripboard (veroboard) and similar prototyping printed circuit boards, which are used to build more permanent prototypes or one-offs, and cannot easily be reused. A variety of electronic systems may be prototyped by using breadboards, from small circuits to complete central processing units (CPUs).
The layout of a typical solderless breadboard is made up from two types of areas, called strips. Strips consist of interconnected electrical terminals.
terminal strips
The main area. To hold the electronic components.
In the middle of a terminal breadboard strip, one typically finds a notch running in parallel to the long side. The notch is to mark the centerline of the terminal strip and provides limited airflow (cooling) to ICs straddling the centerline. The clips on the right and left of the notch are each connected in a radial way, typically five clips in a row on each side of the notch are electrically connected. The five clip columns on the left of the notch are often marked as A, B, C, D, and E, while the ones on the right are marked F, G, H, I and J. When e.g. a skinny Dual inline package (DIP) integrated circuit is plugged into a breadboard the pins of one side of the chip are supposed to go into column E while the other goes into column F on the other side of the notch.
bus strips
To provide power to the electronic components.
A bus strip usually contains two columns, one for ground, one for a supply voltage. But some breadboards only provide a single-column power distributions bus strip on each long side. Typically the column intended for a supply voltage is marked in red, while the column for ground is marked in blue or black. Some manufacturers connect all terminals in a column. Others just connect groups of e.g. 25 consecutive terminals in a column. The later design provides a circuit designer with some more control over crosstalk on the power supply. Often the groups in a bus strip are indicated by gaps in the color marking.
Bus strips typically run down one or both sides of a terminal strip or between terminal strips. On large breadboards additional bus strips can often be found on the top and bottom of terminal strips.