Action Sports with Leigh Roche

Get those thumbs up, Twitter CEO Dick Costolo -- the company's second quarter was worth getting excited about.

NEW YORK (CNNMoney)

Twitter(TWTR, Tech30) shares surged 29% in after-hours trading Tuesday after it posted strong second-quarter sales. Twitter's better-than-expected quarterly report helped allay fears among investors about the company's growth.

Of particular note was Twitter's success with mobile users. The number of Twitter users on mobile grew 29% versus last year. Twitter also raised its projection for total 2014 sales to up to $1.3 billion.

It has been a rough year for Twitter. Shares have fallen by more than 40% since the start of 2014 as investors have questioned how much more Twitter can grow -- and whether it can cash in on its user base. Chief operating officer Ali Rowghani resigned in June, and the company named a new chief financial officer a few weeks ago.

Twitter still lost money in the second quarter -- $145 million, to be exact -- but CEO Dick Costolo touted the company's performance as evidence of "continued momentum."

First Published: July 29, 2014: 4:26 PM ET...