A 'pip' is the smallest price increment.
Example: Currency pair prices used to have 4 digits after the decimal point (e.g. EURUSD at 1.2539), and 0.0001 was the smallest amount by which the price could change (e.g. from 1.2539 to 1.2540).
Now, however, prices can change by one-tenth of a pip, or by 1 fractional pip, also called a Pipette.
Example: USDJPY was usually quoted with 2 digits after the decimal point, e.g. 77.21/77.23, and 1 pip = 0.01. Now you can see the following quotation – 78.513/78.524, where the smallest price change is 0.001 = 0.1 pips = 1 pipette.
So the pip traditionally was the smallest price increment – 0.0001 for almost all currency pairs and 0.01 for pairs with JPY as a quote currency. And despite the fact that a currency pair can now be quoted with more decimal places thanks to more precise pricing, the pip remains the same.