How to get version of magento 2

[1] Via Code

   $objectManager = \Magento\Framework\App\ObjectManager::getInstance();
   $productMetadata = $objectManager->get('Magento\Framework\App\ProductMetadataInterface');
   $version = $productMetadata->getVersion(); //will return the magento version

[2] Go to CLI, Locate your Magento Root Folder & Run below command

php bin/magento --version

Output

Magento CLI version 2.1.1

Which print your Current Magento Version

[3] If you open composer.json on Magento Root You can find as well

"require": {
        "magento/product-community-edition": "2.1.1",

[4] From Admin Side, On Right Hand Side Footer Also You can see

On top of the other answer, you can get the major version (for example 2.1) by accessing /magento_version on your Magento 2 website.