A symlink is a symbolic Linux/ UNIX link that points to another file or folder on your computer, or a connected file system. This is similar to a Windows shortcut.
Example symlink:
espen@espen-Lenovo-G50-80:~$ ls
espen@espen-Lenovo-G50-80:~$ pwd
/home/espen
espen@espen-Lenovo-G50-80:~$ touch myfile.txt
# added content before symlink
espen@espen-Lenovo-G50-80:~$ nano myfile.txt
espen@espen-Lenovo-G50-80:~$ cd ..
espen@espen-Lenovo-G50-80:/home$ ls
espen
# now lets creat a symlink one dir above
espen@espen-Lenovo-G50-80:/home$ sudo ln -s /home/espen/myfile.txt myfile.txt
espen@espen-Lenovo-G50-80:/home$ ls
espen myfile.txt
# now we have a symlink in /home
espen@espen-Lenovo-G50-80:/home$ tail myfile.txt
before symlink
# now lets update the file in /home/espen/myfile
espen@espen-Lenovo-G50-80:/home$ cd espen/
espen@espen-Lenovo-G50-80:~$ nano myfile.txt
espen@espen-Lenovo-G50-80:~$ pwd
/home/espen
espen@espen-Lenovo-G50-80:~$ more -f myfile.txt
before symlink
after symlink yea
# go back to /home
espen@espen-Lenovo-G50-80:~$ cd ..
espen@espen-Lenovo-G50-80:/home$ pwd
/home
espen@espen-Lenovo-G50-80:/home$ more myfile.txt
before symlink
after symlink yea
espen@espen-Lenovo-G50-80:/home$