What is blockchain (detailed definition and description)?

What is blockchain (detailed definition and description)? How is it used (industry use cases, generalized) (non-covid, ie: oil and gas, tobacco, pharma) 2 articlesTHIS IS INTRO PARAGRAPH THAT WILL LAUNCH THE REST OF THE PAPER AND NEED TO FLOW INTO THE 2ND PARAGRAPH.
I have attached instructions from the professor. THE ONLY SECTION I NEED HELP WITH IS THE INTRO, WHICH IS WRITTEN ABOVE(FIRST LINE.. “WHAT ISBLOCKCHAIN…”)TOPICS TO INCLUDE:WHY WAS BLOCKCHAIN ADOPTED SLOWLY PRE-PANDEMIC?Lead into advantages and disadvantages(this is how 2nd paragraph will start)Talk to how covid pandemic accelerated the technology
Please see articles and further instructions in attached document