In Go, primitive data types are the building blocks of any program. These data types include integers, floats, booleans, and characters.

Integers represent whole numbers and can be either signed or unsigned. The signed integer can hold both positive and negative values, while the unsigned integer stores only positive values. The size of an integer varies from 8 to 64 bits depending on the machine architecture, i.e., 32-bit or 64-bit.

Floating-point numbers represent decimal values and can be of either single precision or double precision. Single precision uses 32 bits to store values, whereas double precision uses 64 bits. Go uses IEEE 754 floating point standard to handle floating-point arithmetic.

Boolean data type represents true or false values. It is used primarily in conditional statements to check if a certain condition is true or false.

Character data type represents a single character and is represented using the rune data type in Go. Runes are represented using single quotes, and they use 32 bits to store Unicode characters.

Apart from these basic data types, Go also supports other composite data types such as arrays, slices, maps, and pointers. Understanding and proper use of these data types is essential in writing efficient and maintainable code in Go.