The PICAXE-08 IC is a tiny single-chip computer that you can program in a graphical flowchart-like language or easy to learn BASIC.
This is the least expensive of the PICAXE series, and is an excellent way to "dip your toes" into programming microcontrollers. There's nothing to fear, if what you're programming is this inexpensive!
The PICAXE system is a powerful, low cost microcontroller programming system designed to simplify educational and hobbyist use of microcontrollers. PICAXE chips can be programmed in a graphical 'flow-chart' environment or in easy to understand BASIC.
The PICAXE-08 IC is part of the basic educational lineup of PICAXE chips.
Memory (lines) = Approximate number of lines of program code the chip can hold.
Data Memory = Bytes of EEPROM memory on board. "128 (-Prog)" means 128 Bytes less the space needed for your program. 256+I2C means 256 Bytes + any external EEPROM space you add via the I2C interface).
Polled Interrupt = A process that automatically checks a pin in between each command to see if something has happened (very useful!)