Thailand's digital advertising spending is expected to surpass 20 billion baht this year, up 19% from a year earlier, according to research firm Kantar Thailand.
But the projected growth is still lower than the 36% expansion of 2018, when spending reached 16.9 billion baht.
Arpapat Boonrod, chief executive of Kantar Thailand, said the information is collected from leading media agencies.
In the first six months of the year, online ad spending reached 9 billion baht, Ms Arpapat said, and spending is expected to hit 11.1 billion baht in the second half.
She said this year's slower growth is partly due to the base effect.
Last year, the automotive industry was the biggest digital ad spender, followed by communications and skin care products, Ms Arpapat said. But this year, skin care will overtake communications for second place because 5G has yet to begin.
The communications sector is expected to pick up next year after 5G is rolled out.
Facebook, YouTube, creative and display are expected to occupy the top four spots in terms of spending categories this year, at 5.7 billion, 4.1 billion, 2.1 billion and 1.7 billion baht respectively.
Thais spend six hours on mobile devices out of nine hours daily online, Ms Arpapat said. Artificial intelligence and chatbots are two technologies that marketers believe will have a great impact on online marketing.
Ms Arpapat was speaking at Thursday's seminar on digital media advertising organised by the Digital Advertising Association Thailand (DAAT), an event known as DAAT Day.
"Data-driven marketing is a must for marketers and brands, as it can create effective attraction among users with a precise marketing approach," DAAT president Siwat Chawareewong said at the event, which drew 3,200 attendees.
He said the DAAT will organise training for marketers so they can make use of data to drive online marketing.
Pacharee Permvongusawa, head of the digital business unit at Publicis Media and a member of the DAAT committee, said the number of daily active Twitter users in Thailand has grown by 30% from last year, the biggest rise in the world, which saw a 9% expansion. The number of Twitter users in Asia-Pacific is up 20%.
Twitter offers a new feature to display pop-up adverts on feeds and will soon have content shared with its partner Thairath TV under the shared ad revenue model, Ms Pacharee said.
Paruj Daorai, managing director of Digitas Co, a connected marketing agency, said data-driven marketing will enable content to reach individuals via various platforms.
For example, long video formats will pop up on YouTube during the evening while short ones appear on Facebook.
Narin Yenthanakorn, a member of the DAAT committee and chief operating officer of I-DAC Thailand, said marketers need to focus on data strategies and create content that can meet business goals.