What are comments in Java?

Comments in Java are lines of code that are ignored by the compiler and are used to provide information or explanations about the code. They are used to make the code more readable and understandable for other programmers or for future reference. Comments can be used to describe the purpose of a class, method, or variable, provide instructions, or disable a piece of code temporarily. There are two types of comments in Java:

1. Single-line comments: These comments start with two forward slashes (//) and continue until the end of the line. They are used to comment on a single line of code.

Example:
```java
// This is a single-line comment
int x = 5; // This is another single-line comment
```

2. Multi-line comments: These comments start with a forward slash followed by an asterisk (/*) and end with an asterisk followed by a forward slash (*/). They can span multiple lines and are used to comment on multiple lines of code or to create a block comment.

Example:
```java
/*
This is a multi-line comment
It can span multiple lines
*/
int y = 10; /* This is another multi-line comment */
```