Broadcast systems and television standards

There are several different television standards, PAL, NTSC and SECAM. These three different standards are al used in different places around the world. Each of these are used in different places around the world:

Both PAL and SECAM are 25fps, NTSC on 25fps. 
PAL was developed by Walter Bruch, in Hannover, Germany. PAL was invented due to several errors with NTSC were highlighted, one of these was colour tone shifting. 
SECAM had started being developed in 1956, PAL Stands for PHase Alternating Line.
The first version of SECAM was released in 1961and was the first european colour standard that started in france. It was named SECAM I but improvements had been made over time to improve image quality. This version was called SECAM II. Further improvements were made on the system, hence it was named SECAM III A, Then SECAM III B. NTSC (The National Television System Committee) Was established in 1950 in the united states, it used 25fps,and has 525 scan lines, making it more detailed.NTSC was made in the united states and the NTSC was established by the Federal Communications Commission (FCC).NTSC video signals are still used in cctv today.

Advantages/ Disadvantages
PAL:
PAL Has greater resolution than NTSC.
PAL Automatically corrects colours as it has alternating line.
PAL has worse quality an the worst conversion rate out of the three.
PAL has excellent colour stability, and it used in over 65 different countries. 
NTSC:
NTSC Has tint controls that corrects the colour manually corrected. 
NTSC has the worst quality of the three. NTSC runs at 30fps whereas PAL only runs at 25fps, but NTSC has a much smoother clearer image hence it is better for things like sports.
SECAM:
SECAM Has the highest resolution of the three (SECAM, PAL and NTSC).

More recently cable (Virgin and BT), Satellite (Sky) and digital (Freeview) are used to broadcast television. Freeview is free to use and was launched in 20002, when the BBC and Crown Castle (Now Arqiva) officially took over the digital terrestrial television licences. Free-view was made in 2002 may 9th and to this day is one of the only free to air broadcast systems, this was made when BBC and crown court took over british terrestrial television.

Sky was founded in 1990, it is a british satellite broadcast. In the UK and Ireland Sky has over 10 million subscribers. 21st century fox have since owned 39.41% of the company. 

Cable TV(Virgin and BT) was invented in the United states in the 1980's.There are two different standards for cable television, analogue, that would carry standard definition, and digital cable. This could carry High definition. 

Over the internet you can also access sites such as  4oD so view channels and series that you may have missed for free, but the downside to this is that they are not live and the shows are only online on the website for so long before they are deleted and removed.This is very similar to freeview, in freeview you can view movies and television series in advance of the official release sometimes, You have to pay every month for these services.

Advantages/ Disadvantages:
Sky has more channels than cable TV and satellite but it is way more expensive as if you want to buy a large amount of channels you have to buy them monthly and are in bundles so you cant control exactly what you are paying for. 

Viewing on the internet on sites like 4oD is free unlike if you was to buy something on sky but you can only watch a programme if it has been on tele recently whereas on sky these are repeated all of the time and if you get sky + you can record them.