HTTPS Everywhere is an extension for the Chrome browser, which ensures that your connection to certain websites* is accomplished over secure hypertext transfer protocol (HTTPS).
HTTPS Everywhere will automatically switch thousands of websites from insecure "HTTP" to secure "HTTPS". The extension can protect you against numerous forms of surveillance and account hijacking, and some forms of censorship.
In theory HTTPS Everywhere should work exceptionally well, but this isn't the case for all websites.
It only works for those websites which support encrypted communication but do not have it enabled by default. This is achieved by rewriting the requests to these web locations so that the connection is done in a secure manner.
Overall, HTTPS Everywhere works automatically in the background, and doesn't interrupt you to make any adjustments. The HTTPS Everywhere extension increases your security during your browsing sessions, but it isn't perfect as not all websites are supported.
*Not all websites are supported.