Page 30, Column 2, Paragraph(s) 1, Core Rule Book
Click (Click): The basic unit of work in Android: Netrunner. Playes spend their clicks to perform actions and trigger abilities.

The click is the basic unit of work in Netrunner, and it is one of the key components that separates Android: Netrunner from other games in terms of play structure. Each turn, a player has a certain number of clicks to spend taking actions, which s/he can do in any combination of action available to him/her. Some actions are built into the game — like drawing cards, playing cards, and taking credits — and some actions can be opened up by installing cards with click abilities on them.

A click is always represented by Click, even in multiples.

Page 5, Column 2, Paragraph(s) 6, Core Rule Book
Click: This is the basic unit of work, represented by Click.
Page 22, Column 2, Paragraph(s) 4, Core Rule Book
Click: This symbol stands for a single click. Multiple clicks are represented by multiple symbols, such as ClickClick, which means "two clicks."

FAQ 1.4.31Edit

From the FAQ. Also number 1.5.30

Clicks are tracked as a running total. A player is never "in", "on", or "during" a click. They are spent from a set number available, which can be increased or decreased by card effects: ClickClickClick is the default for the Corporation, and ClickClickClickClick is the default for the Runner.

Page 11, Column 2, Paragraph(s) 2, FAQ
The Corp has two copies of Director Haas installed, one rezzed and one unrezzed. The Corp spends four clicks and then rezzes the second copy. Does the Corp have an additional click to spend?
No. Clicks are tracked as a running total and not individually. The Corp still has 4 clicks to spend on his turn, and he has spent 4 clicks, whether or not the additional click came from a different card.
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