Tab feature in Yahoo Mail

[shaharhada]

Can somebody explains me the meaning of the underlined text:
A redesigned version of Yahoo Mail, which the company introduced in October, has met with a mixed reaction by users. Many users have griped that the new versions eliminated popular features such as “tabs”.
What is the meaning of griped?
Which feature the meaning by the word "tabs"?
From:

https://www.newsmax.com/SciTech/yahoo-email-outage/2013/12/11/id/541316/

 

[USAFRet]

"griped" - "complained"

Tabs is like when you have multiple websites open in your browser...those 'tabs' across the top.
Apparently the Update did away with that feature.