HTML, for HyperText Markup Language, is an markup language used for creating web pages.
This language is clearly oriented for designing visual objects.
It is commonly used with other languages, like CSS / JS / PHP, where each one has its specificity.
Everyone can be written in the same HTML file but it is not very confortable for coding and understanding, so each language has its own file format.
CSS, for Cascading Style Sheet, clearly defines how the webpage looks like. In this file, we can define each property for each part of the web page, as the color, the border style, the size, etc.
JavaScript, or JS, is a high level and interpreted programming language. A Javascript is run on the client, compared to PHP which is run on the server.
Basically, HTML (and CSS) is a fixed page, where nothing is moving.
So Javascript allow the webmaster to animate the page over time.
For example, it is used for user interface animations and also to modify what (and how) is written the contents of the page.
Javascript is like the "brain" of the webpage because this is in that place that each computation is done.
HTTP, for HyperText Transfer Protocol, is an application protocol through the web data (written as text) are transferred between clients and servers.
Released in october 2014, this is the version 5 of HTML programming language.
Compared to the older ones, it allow the webmaster to insert easily shades (canvas), dynamic things and multimedia objects without using plugins like Flash, Java, Windows Media or QuickTime applications.
These ones are also known for a lot of security problems, so HTML5 was a very useful evolution of HTML because multimedia objects are easy to be implemented, final user doesn't have to have extra applications on his computer to run multimedia things, and security is improved.
Dynamic HTML is like a set of technologies used to create interactive and animated websites. This is a combination of a static presentation (text and contents) with HTML, a scripting languages (as JS) and a presentation definition language (CSS). DHTML allows scripting languages to change variables in a web page's definition language. Consequently, HTML pages are not only fixed, they can be dynamic and that thing is interessant to make more user-friendly user interfaces.
To begin with HTML and JS, here is a basic application where you can create a temporary person list. User can only add items, and these ones are removed if the page is reloaded.