Byte Data Type
In Java, Byte is a data that represents an 8-bit signed integer. It can hold values from (—128) to 127.
Other integer types in Java include short (16 bit), int (32 bit), and long (64 bit). This is the one that takes the least memory space.
Byte Arrays
Data from file is read as byte arrays. When directly used, they're just byte values. Byte arrays can be converted to other data types as needed. In such cases, the bytes in the array are interpreted according to the target data type.
For example, if we say that the byte array contains UTF-8 character set data, then two bytes are processed together to translate it into a single Unicode character. More details can be found in the bytes encoding and signed numbers pages.
Byte is an integer only when a variable is explicitly declared as byte. Otherwise, byte in always just represent 8 bits and can be used to interpret anything.