Robotic process automation (RPA) is software that copies what a person does on a computer screen, such as typing an invoice into the ERP, and then does it by itself. The "robot" is not a machine. It is a program, often called a bot, that clicks buttons, types into fields and reads screens, in the same way as an employee.
How is a bot built? A developer records or draws the steps of a task in the RPA tool: open this application, click this field, copy this value, paste it there. The bot then repeats those steps, hundreds of times a day. It uses the same screens that people use. So it does not need an API, the fixed format through which one program asks another for data. This is why companies first used RPA: for old systems that offer no other way in.
Take, for example, a medicine distributor in Ahmedabad. Its accounts team receives about 400 supplier invoices a month as PDFs. Typing each one into the ERP takes an employee about six minutes, or 40 hours a month in all. The company builds a bot for the task. Every 30 minutes, the bot opens the accounts inbox and saves each new invoice. It sends the PDF to intelligent document processing software, which reads the supplier's GSTIN, the invoice number and the amounts. The bot logs in to the ERP, opens the purchase order that the invoice refers to, and checks that the amounts match. If they match, it enters the invoice. If the invoice amount is higher than the purchase order, it does not enter it. Instead, it passes the invoice to a person, as an exception in case management software. In a typical month, the bot enters about 360 invoices and passes about 40 to people.
There are two kinds of bot. An unattended bot runs on a server by itself, on a schedule. An attended bot runs on an employee's own computer, and does part of a task when the employee asks it to.
RPA has one main weakness. The bot depends on the exact layout of each screen. If the ERP is upgraded and a button moves, the bot can stop, and someone must fix it. So companies first find out which tasks are worth automating. Process mining and task mining show where people spend their time.
RPA companies are now adding AI. A bot can be told what to do in plain English, through agentic process automation. An AI agent can also read an email, work out the request and decide which steps to take. Most RPA companies now sell such agents beside their bots, as AI agents for enterprise work.