VIM: Jump Back To Previous or Last Cursor Position

Writing shell scripts in vim I usually go search for functions or something. Copy lines and then go back to where I was and modify the code. However, I need to manually navigate way back to the previous / last position. How can I automatically go back to where I was when I started my search operation under vim?

Tutorial details
Difficulty	Easy (rss)
Root privileges	No
Requirements	None
Time	N/A

Vim is a text editor that is upwards compatible to Vi. It supports the following markers and moving about keys:

[a] '. : Jump to last modification line. [b] `. : Jump to exact spot in last modification line [c] CTRL-O : Retrace your movements in file in backwards. [d] CTRL-I : Retrace your movements in file in forwards.
From the vim help files:

Jumps are remembered in a jump list. With the CTRL-O and CTRL-I command you can go to cursor positions before older jumps, and back again. Thus you can move up and down the list. There is a separate jump list for each window. The maximum number of entries is fixed at 100.

Example

Open a text file called functions.bash, run:
$ vim functions.bash
Move cursor or go to line # 300 by typing the following vim command
300 shift g
Search for a shell function called _addNfsClientUser
/_addNfsClientUser
To jump back to line # 300 or previous position press CTRL-O (press and hold Ctrl key and press letter O). To jump back forwards press CTRL-I (press and hold Ctrl key and press letter I).

See also

Type the following command to get helpful info about jumping:
:help jumplist

Category	List of Unix and Linux commands
File Management	cat
Firewall	Alpine Awall • CentOS 8 • OpenSUSE • RHEL 8 • Ubuntu 16.04 • Ubuntu 18.04 • Ubuntu 20.04
Network Utilities	dig • host • ip • nmap
OpenVPN	CentOS 7 • CentOS 8 • Debian 10 • Debian 8/9 • Ubuntu 18.04 • Ubuntu 20.04
Package Manager	apk • apt
Processes Management	bg • chroot • cron • disown • fg • jobs • killall • kill • pidof • pstree • pwdx • time
Searching	grep • whereis • which
User Information	groups • id • lastcomm • last • lid/libuser-lid • logname • members • users • whoami • who • w
WireGuard VPN	Alpine • CentOS 8 • Debian 10 • Firewall • Ubuntu 20.04