What is the name of the system that replaced stairs for disembarking aircraft? Back in the day, or in old airports, or airports that have not upgraded their systems, passengers disembarked in aircraft using stairs, through rain and or snow and extreme weather, sometimes having to delay disembarking because of bad weather in turn delaying themselves, the airport and the aircraft schedule. Today there is a new weather proof system where passenger disembark the aircraft and find themselves in the air conditioned airport, devoid of all the unfavorable extremes, devoid of delays.  What is the name of this system and when was it introduced?
(throughouthistory.com)

Shown above is a telescopic corridor at London Gatwick airport c. 1930's (I had to make it interesting).

For today's system, the name you are looking for is jet bridge. It's also known by other names. There is also a rarer system called mobile lounge.