Built-in packages

Much like every programming languages, Go has its own built-in pkgs. There is no difference as to how you write main program and how you write a package. These built-in packages also uses other built-in packages which you can find when you open anyone of them. A general question arises "When they themselves uses built-in package, why can't we use them directly too?" and this is appropriate but the reason to hide such implementation is to avoid developers needing to develop low level code and focus on business logic. You can find them in C:/Go/src in your system. Below you can find some of built-in packages categorized based on application or their use.

compress files/folders

1. bzip2

2. flate

3. gzip

4. lzw

5. zlib

crypto

1. aes

2. cipher

3. des

4. dsa

5. hmac

6. elliptic

7. md5 et al.

database

1. sql

2. sql/driver

os

1. os

2. exec

3. signal

4. user

io

1. io

2. fs

3. ioutil

log

1. log

2. syslog

net

1. net

2. http

3. http/cgi

4. net/http

5. mail

6. rpc

7. smtp

8. url

regexp

1. regexp

2. syntax

other packages can be found here under standard library section