This is an updated version of a glossary originally published in the book chapter "Using the Web to Teach Economics", explaining some basic terms associated with the Web.
blog: (from ‘Web log’) an online journal that is easy to update with short messages and links. The software takes care of generating pages and indexes from the various items that you ‘blog’. It is surprisingly quick to set up a blog on a hosted service.
browser: the software with Web pages are viewed, for example, Chrome, Firefox, Edge, Safari or Opera. Although in theory they should all display web pages the same way, there are subtle differences.
DM (Direct Message): This is a message sent from one user to another, or to a group, in private. Social software such as Twitter allow DMs in addition to public posts; it's important not to confuse the two! Some sites call them Private Messages or PMs.
domain: a named location on the internet which can be owned by an organisation or individual. In the case of http://example.org/index.html the domain is example.org. Most domains are bought and sold commercially. There are restrictions on specialised domains such as those that end in .ac.uk (UK academic) or .gov (US government) but almost anyone can own a .org, .com, .org.uk, .co.uk and so on.
groupware: software that enables a group of users to collaborate by sharing messages and documents over a network. VLEs (q.v.) are examples of groupware.
HTML (HyperText Markup Language): the language in which Web pages are coded. These are essentially structured text documents that point to other pages using URLs (q.v.).
IM (Instant Messaging): software that tells the user when friends are online and enables them to chat in real time.
linkrot: if a list of links is not maintained, its usefulness will erode as the linked sites move, disappear or update their content so that it is no longer relevant. Section 3.1 discusses how to combat this process.
lurking: reading the contributions to a virtual community (q.v.) without actively participating. It is usually good etiquette to lurk in a community for a while before contributing.
open source: The underlying code of some software is published and reviewed in a manner analogous to academic research. It is added to the public commons rather than kept as a proprietary secret. These “open source” programs often cost nothing, yet are superior in many respects because they can be scrutinised and customised by other programmers. There are open source programs for just about any application, including browsers (q.v.) and groupware (q.v.).
paywall: A lot of the Web's content is not freely available to everyone but requires a paid subscription. This is still the case with a lot of academic research and for some online newspapers and magazines. Users following the link will not see the document but get a "paywall" asking them to subscribe or pay a one-off fee. Those of us working in universities often benefit from institutional subscriptions, so a link that works immediately on the university network might show a paywall to users on other networks.
permalink: a link to a specific piece of content. Let's say you find an interesting post on the front page of a blog: newer posts will eventually push that post off the front page. To return to that post, or to recommend it to other people, you need to look out for its permalink. In a wiki context, "permalink" has a slightly different meaning. Pages on a wiki (q.v.) change over time as they are edited by its users, so a permalink is a link to the state of a page as it existed at a particular date and time.
plug-in: a piece of software that is added to a browser (q.v.) to give is extra functionality. Plugins used to be necessary to view resources such as interactive tutorials or video, but as the web evolves, more interactivity happens without needing this extra software. You might still encounter educational sites that only work if you have the Flash plugin installed.
PM (Private Message): see DM
social software: software, running on an individual’s computer or on a website, with which users can create personal profiles, form groups and exchange messages. They can also ‘rate’ each other and so build reputations.
streaming: It used to be the case that to watch an online video, you first had to download the whole file. Watching a video (or listening to audio) while it downloads is called streaming. Most video sharing sites such as YouTube and Vimeo enable streaming. With some sites, such as Periscope or Twitch, there is not a file as such, but a continuously broadcast, live video feed.
thread: some discussion forums present the messages chronologically, without respect for topic, but others show them linked by topic, each contribution appearing underneath the message it is responding to. This is called ‘threading’ and a debate on a particular topic is called a thread.
URL (uniform resource locator): the address of a particular file on the Web, which works from any part of the internet. An example is http://www.google.com/options/.
virtual community: a group of people communicating over a network on a shared interest, possibly via a moderator. This might be through an e-mail list, an online discussion board, a chat room or social software (q.v.).
VLE (Virtual Learning Environment): a package to help lecturers create a course website with a minimum of technical skill, including tools for discussion and document sharing.
vlog: short for "video blog". A regularly updated series of videos in which people talk about what is currently happening in their fields, in the news, or in their lives.
web log: see Blog.
wiki: a wiki is a website that visitors can edit using their browser. Groups can use a wiki to author documents collaboratively. An example is Wikipedia.org , the collaborative encyclopaedia.
WYSIWYG (What You See Is What You Get): an editing interface which is like a simple word-processor, where you add formatting to text. In some discussion software, adding bold text, italics or links requires a specific "code". WYSIWYG interfaces are more intuitive and immediate.