What are invalid clicks?

[praveenitech1]

Clicks from different proxies are invalid

[riyajindal]

Invalid traffic includes any clicks or impressions that may artificially inflate an advertiser's costs or a publisher's earnings. Invalid traffic covers intentionally fraudulent traffic as well as accidental clicks.

[Arpita]

Understand your ad traffic and site visitors. ...
Avoid partnering with untrusted / low-quality parties. ...
Don't click on your own ads, even if you think it's okay to do so. ...
Double- and triple-check your implementation. ...
Use the authorized sites feature to prevent unauthorized use of your ad code. ...
Consult the AdSense Help Forum.