What exactly does IBM's Clearquest software do?

I tried to read the wikipedia page on IBM’s clearquest software, but I am left with no idea. Is there some plain-English explaination for what exactly it does?

It’s a project organizer, with chart and report features. Probably utilizes the Ghantt process for time based projects.

It is (was?) primarily bug-tracking software. If you are familiar with bugzilla, JIRA, Visual Intercept, PVCS Tracker – it is the same thing.

Sorry, I realized from your OP that you may not be familiar with bug-tracking software at all.

Consider a group that is developing a software application, such as Microsoft Word. As the software developers complete their work they create test builds for the Quality Assurance (QA) team to test. The QA team will install the software and test (use) it. Often the QA team will have a test-plan that consists of a whole bunch of tests that should run on the software. One test might be 'Verify that pressing the Indent button on the toolbar indents the text that is highlighted". For a big product like Microsoft Word, there will be a ton of these test cases.

As the QA team runs tests, they will discover that some of the tests fail. For each failed test, the QA team will enter a report in the bug-tracking software. The bug report will contain a lot of information – what test failed, what version was tested, who found the bug, etc. The bug will then be assigned to a software developer to fix. When the developer fixes the bug, he will update the bug report so that the QA team knows it is fixed and should be re-tested in the next build.

The above description is an over-simplification and there are as many varieties of process as their are companies (or even development teams), but it should give you a feel for what the software does.

Bug-tracking software is basically a giant to-do list that a team can share to track what needs to be done to complete their project.

sort of.

It is a workflow automation tool. It is most commonly used for bug tracking, but it can be configured to do a lot of other things.

What’s a workflow?

A simple linear workflow:

Imagine you want to follow some process like fulfilling an order.

  1. customer calls operator and operator enters data into system
  2. warehouse worker sees order in system and pulls items from inventory. He marks the order as “pulled”
  3. Worker sees in system that order is complete and bills the customer’s credit card. Marks in system that charge has been made
  4. Shipping department sees in the system that the order is cleared to ship. They pack the merchandise and tell UPS to pick it up.
  5. System sends notification to customer with tracking number.
    But what happens if in step 2 some merchandise is not available?
    then we go to step 6 (notify customer of backorder) instead of step 3.

You can easily imagine the flow become a complicated flow chart of steps to take depending on the actions occuring in the current state with all sorts of loops and contingencies.

What this tool really does is allow people to create a computer system that tracks their business’s workflow.

One really common workflow is bug tracking (which gets a lot more complicated once customer reported problems and service requests enter the equation), but it is by no means the only thing that it can do.

I used parts of ClearCase back when it was a Rational product.

ETA: Sorry, I misread the OP. Carry on.