sending different types of data

hi guys:
I can send data from slave arduino to master arduino, but I just have a problem to send sensor data to master. What kind of data type I2C sending between master and slave? BYTE or something else? If that's BYTE what should I do to turn those data into BYTE and make it still read able after the data was transmited to master?

What kind of data type I2C sending between master and slave?

It's your code. What type are YOU sending?

The only thing that the library can send is bytes, but everything else is a collection of bytes.