What Exactly is a Custom ROM?

Hey people this is my first post, I don't wanna rush up directly to Apps,ROM's,Kernels,etc.

First let us know what are they exactly :)

ROM

In simple words, a ROM is the basic Operating System ( It may vary as Gingerbread, Honeycomb or Jellybean) on which your mobile runs. Just like Windows 8 or Mac on your computers.

There are 2 types of ROMs:

1.Stock ROM

2.Custom ROM

The basic operating system your phone works when you buy them is known as the STOCK ROM. It has all basic needs & it is secured OS, as it is not rooted at the beginning. It is the safest OS you can have

On the other hand, we have the most Interesting, mind-blowing and Rocking ROM, known as CUSTOM ROMs.

- Interesting because we have a wide range of   User Interfaces ( UI ) which we can choose based on our taste and preferences 

- Mind-blowing because you get to explore things, which you had never thought your mobile could do.

- Rocking because, words cannot explain ;) Feel it yourself.

Advantages of Custom ROMs

• There are frequent updates for your software, bringing up developments,fixing bugs and build new features. As the developers who develop the Custom ROMs have no restrictions in bringing up the updates.
• These are a lot faster, efficient and use much less memory with help of tweaks
• The developer Remove useless garbage, such as carrier installed apps.
• The developer optimize the kernel. For example, an undervolted kernel can provide a much better battery life than the stock one.

Disadvantages of Custom ROMs

• If you screw up while flashing custom ROM, you may brick your phone, which makes the mobile unusable.
• As developers are continuously developing ROMs, you'll frequently face bugs while operating it.