on vidio A look inside home electrical panel.

 Note that in this video the panel is new and has no external circuits connected yet.  When wired in and active there is a lot of exposed live metalwork that poses a shock risk.  Changing a consumer unit is not a simple DIY task due to the presence of a high current supply that poses a shock and burn hazard if touched or bridged.

In the UK we have a really simple electrical system.  Just a three phase system with 240V between each phase and neutral and 415V between any two phases.  (230V/400V under European tolerance standards.)
A typical home will get a single phase and neutral with the three phases spread amongst homes in a street, while a factory or commercial premises will usually get all three phases.
The higher voltage means lower current and the single phase means that our consumer units (home electrical distribution boards) are very compact and simple inside.
Traditionally they contained an isolator with a busbar that went along a horizontal row of breakers, but these days the breakers are often grouped in sections, each protected by its own main RCD/GFI.  This allows the RCD/GFI to protect all the wiring in the circuit and also ensures that if a leakage fault does cause an RCD/GFI to trip, it only turns off a small number of circuits in the house.  In some instances every single circuit may have its own RCBO (Residual Current Breaker with Over-current) which protects each circuit against overcurrent and fault leakage.
The use of a DIN rail for mounting the breakers means that the panel can accommodate other modules if desired.  Commonly things like time switches and power supplies.  Alternatively a consumer unit can be used purely as a handy housing for a row of DIN modules with the added advantage of integral power busbars.
A typical British home gets a 60A utility fuse these days, although for larger homes or applications like vehicle charging that can be upgraded to a higher value if the incoming cable is suitably rated.
Typical circuits in a consumer unit are:-
Lighting.  A radial circuit protected by a 6A circuit breaker.  Usually wired with 1mm or 1.5mm CSA cable.  The circuit usually bounces from room to room passing through a ceiling rose connector that makes it a very versatile system for lighting.
Radial power.  Often a 16A breaker feeding a special application like a heating boiler control system or immersion heater.  Usually wired in 2.5mm CSA cable.
Radial circuits are also used for high current loads like cookers and showers with suitable cables and breakers.
Ring power circuit.  An unusual approach to running lots of high current sockets with a loop of cable that starts and finishes at a 32A breaker.  Usually wired with 2.5mm CSA cable.  People make entire careers out of inventing new and pointless ways to test ring circuits.  Sometimes called a ring main as the first circuits were based on power distribution ring mains that are used in the electrical utility industry.  Now called ring final circuits, a new name invented by the department of paperwork.

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