Encryption is getting importanter now because the internet has grown alot. We have internet everywhere. Even in our pockets. There are whole companies who are based to provide service on the internet. It's kinda weird that these companies are selling something you can't hold in your hands.
When you are trying to visit a website, your web browser is establishing an connection with the web server by using the HTTP protocol. This happens by establishing a plain text connection.
Using an unencrypted, plain text connection is not a big deal for normal websites where there are no personal data stored onto it, like this site. Important services like internet banking, web e-mail clients or a payment service require the use of an encrypted connection.
The dangers of using a unencrypted HTTP connection:
An encrypted connection prevents that any interceptor can read the data. If someone would use a network sniffer, the connection will be shown but all the data is encrypted.
BadSSL.com, check if your browser accepts invalid, insecure certificates.
Test your website or servers supported encryption. This site also tests your server for vulnurabelities.
Mozilla has launched a free service to generate your own TLS certificate