RECAP:

First, lets recap. Vim plugins are used to add functionality to vim. That functionality can be syntax highlighting, bracket matching, mode switching, easy file searching etc. Pretty much, there's a plugin for every functionality that is not built-in to vim.

INSTALLATIONS:

The way of installation varies with the type of plugin manager you are using. Almost all plugins are either developed or backed up on github. Most plugin managers make it trivial to install plugins from github repositories.

For pathogen, clone the plugin in the bundle folder in the .vim directory in your home folder.

For Vundle, NeoBundle, Vim-Plug, add

Plugin '<key>'              " OR
NeoBundle '<key>'           " OR
Plug '<key>'

respectively to your .vimrc. Where <key> for a plugin with github link https://github.com/scrooloose/nerdcommenter, would be

scrooloose/nerdcommenter.

1. AIRLINE: I used to think I could live without this plugin. It usually made the vim startup a bit slower, and I never liked that. But once I started working on actual projects, Airline became an essential plugin for me. Airline displays a top and a bottom status bar in vim, with information about open buffers, current mode, text encoding, git branch etc.

2. NERDCOMMENTER: Nerd Commenter makes commenting and uncommenting lines of code extremely simple. It is ideal when debugging code as you can comment out lines with a simple keystroke irrespective of the language your code is in.

3. ZEAVIM: This is an integration plugin for Zeal app. You can jump to the documentation of any term of any language just by pressing a sequence of keys from inside vim.

4. AUTO-PAIRS-GENTLE: You know how every code editor auto completes your ending braces? This plugin gives you the same functionality inside vim.

5. EASYMOTION: This comes last in my list because I've almost stopped using it. You can jump to any character or word in a particular FOV using a few keystrokes. I however find it more natural to use relative numbering to move up and down and f key to move left and right on the same line.

I would also like to mention AutoComplPop and YouCompleteMe plugins for syntax completion. However, I feel that vim's functionality is best expressed using the inbuilt keys, as you can control the type of completion (filename, line, word, syntax, ctags etc.)

I also recommend that you look at other users' vimrcs for more plugins. You never know what you'll discover. Here's mine to start with.

BEST OF LUCK CUSTOMIZING YOUR VIMRC!