The search module adds the ability to search for content by keywords. Search is often the only practical way to find content on a large site. Search is useful for finding users and posts by searching on keywords.

The search engine works by maintaining an index of the words in your site's content. It indexes the posts and users. You can adjust the settings to tweak the indexing behaviour.

The poll module can be used to create simple polls for site users. A poll is a simple multiple choice questionnaire which displays the cumulative results of the answers to the poll. Having polls on the site is a good way to get instant feedback from community members.

Menus are a collection of links (menu items) used to navigate a website. The menu module provides an interface to control and customize the powerful menu system. Menus are primarily displayed as a hierarchical list of links using a highly flexible blocks feature. Each menu automatically creates a block of the same name. By default, new menu items are placed inside a built-in menu labelled Navigation, but administrators can also create custom menus.

The taxonomy component is one of the most popular features because users often want to create categories to organize content by type. A simple example would be organizing a list of music reviews by musical genre.

The news aggregator is a powerful on-site RSS syndicator/news reader that can gather fresh content from news sites and weblogs around the web.

The contact module enables the use of both personal and site-wide contact forms, thereby facilitating easy communication within the community. While personal contact forms allow users to contact each other by e-mail, site-wide forms allow community members to contact the site administration from a central location. Users can specify a subject and message in the contact form, and also request that a copy of the e-mail be sent to their own address.

The comment module creates a discussion board for each post. Users can post comments to discuss a forum topic, weblog post, story, collaborative book page, etc. The ability to comment is an important part of involving members in a community dialogue.

The blog API module enables a post to be posted to a site via external GUI applications. Many users prefer to use external tools to improve their ability to read and post responses in a customized way. The blog api provides users the freedom to use the blogging tools they want but still have the blogging server of choice.

The blog module allows registered users to maintain an online journal, or blog. Blogs are made up of individual blog entries, and the blog entries are most often displayed in descending order by creation time.

There is an (optional) Blogs menu item added to the Navigation menu, which displays all blogs available on your site, and a My blog item displaying the current user's blog entries. The Blog entry menu item under Create content allows new blog entries to be created.

Profiles allow people (members) to get to know each other better. A profile is all about the member.  The individual may add information about themself  or share some posts, photos, and videos to let folks know what they are all about.  It is possible to put controls in place that allow a member to decide exactly what information is public and what's available only to the people  identified as friends or colleagues (or whatever you want to name your friend sets).