jQuery is the part of our life on the internet since around 8 years. Over the years Web Development has been extremely improved and a lot of amazing products and jQuery Plugins built on jQuery, therefore upgrading and improving the jQuery library is a must. Hovewer, jQuery has been changed along with the Web Development, the founders of jQuery also tried to keep the compatibility of the older versions. This way it can supports the most of web development best practices of the present.
In 2013, the team started to release two different jQuery versions to create a slimmer version, but preserve the browser and API compatibility. The one of them released with version numbered 1.x provides the best compatibility for browsers and the second one starting with 2.x dropped support for Internet Explorer 8 and below. Both of them has the same APIs, but it has some differencies with the internal implementations.
The next jQuery release will contains some different solutions. The most success version with 1.x will be jQuery Compat 3.0 and the slimmer version will become to jQuery 3.0
Some deprecated methods will be removed from the new jQuery versions, therefore jQuery Migration Plugin also get a new update.
The jQuery Team recommend to use the jQuery Compat version for the most of the websites in the future. For websites with cutting-edge technologies and want to lacks the compatibility of older browsers, they can suggest the jQuery 3.0 package.
If you would like to follow the news about the releases, you can read more on the jQuery Blog.