Android is a Mobile Operating System. It has many versions just like the IOS. Android has the Following versions(Starting From The Latest)
1. Noughat 7.0(Still unofficial)
2. Marshmallow 6.0-6.0.1
3. Lolipop 5.1-5.1.1
4. Kitkat 4.4-4.4.4
5. Jelly Bean 4.1-4.3
6. Ice Cream Sandwich 4.0-4.0.4
Now the Older Versions(Not anymore in use Nowadays)
[login to view URL] Comb 3.0-3.2.6
8. Ginger Bread 2.3-2.3.7
9. Froyo 2.2-2.2.3
These Are the versions. The best among them now is the Lolipop. Its the most widely used android version. U can even install these versions unofficially. Like For example- I had a Phone The Samsung Galaxy S3. So, the Samsung company only have given the Jelly Bean(4.3) as the latest version. But installed Marshmallow(6.0). Now the question Appears HOW? I rooted my phone then i installed a Custom Recovery called TWRP. Then i downloaded the unofficial ROM CM13. Then i Installed The Gapps(GOOGLE APPS) and i got Marshmallow version on my phone. Android also have many problems:
[login to view URL] phone. Brick are of 2 types
A. Soft Brick- It occurs when there is a software error. It causes a BOOTLOOP or the phone doesn't boot up due to wrong flashing or something went wrong while Rooting.
Solution- Download the specific Phones firmware provided by the company. Then RE-Flash it.
B. Hard Brick- Your'e Phone doesn't boot up at all. It is caused due to flashing the wrong ROM which isn't of that device. Most of the times the phone's touch stop working. Most of the times it doesn't have a solution. U gotta put its own firmware back.
2. Google Play Store Crashing- It happens most of the times because u maybe must be having a corrupt cache or something else.
Solution- Go to Settings<Apps<Go to all<Swipe Down and u will find Google Play Store<Wipe cache and data<Restart your'e Phone
3. Android Not Reading micro SD Card- Sometimes its faulty or has some pirated or Faulty software or some game.
Solution- Format The SD card. If still not working change the sd card (must be a faulty one)
4. Phone is running very slow- It happens due to installing many games or using up all the memory.
Solution- Do a backup of everything and perform a data factory reset. By pressing the Home Button+Volume Up button+Power Button. Do a Factory reset. When done reboot the system now.
5. Camera is crashing- It happens due to some bug
Solution- Go to Settings<Apps<All<Camera<Clear Data<Restart the phone
Rest all works Fine.