The link below has an easy explanation.
Airline Reservation System Some More Examples are -Payroll Processing SystemTransport Ticket Reservation SystemPurchase Order Entry SystemMarkets Tabulation System
Some examples of transactions are All a sudden, Then, First, After that, Finally, First of all, and so on...
disadvantages of transaction processing system
Examples of decision-support systems include applications for analysis of sales revenue, marketing information, insurance claims, and catalog sales.