A TV commercial is an advertisement for your product or service. It usually has a limited duration – 15 seconds, 20 seconds, 30 seconds, 45 seconds or even 60 seconds. The longer your commercial the more you must pay the network to air it. Now, YouYube pre-rolls have started acting as TVCs in the internet world.
Here's an example 
Companies and brands that need to get the word out about their awesome product or service, those who want to garner leads, get sales, drive traffic…basically anyone who has a product or service that they wish to create awareness about and/or sell. The best way to do this? Advertise on sites that have premium video content that people are consuming. Sites like YouTube, HuffPost, ScoopWhoop, The Viral Fever... the list goes on
In the days before the Internet, TV Commercials were really the only way to reach you target segment. These commercials were aired on various television channels, in various time slots and in-between programmed content. Based on the kind of programmed content and time slots, brands could target their customers.
You can, now, ‘air’ your ad on YouTube and most sites with premium video content or through rich banner ads. Users can even take action after watching your ad – like filling up a form, going to your website or subscribing to your social channels. Programmatic advertising has changed the way brands reach and pay for their audiences. Programmatic advertising helps automate the decision-making process of media buying by targeting specific audiences and demographics. Programmatic ads are placed using artificial intelligence (AI) and real-time bidding (RTB) for online display, social media advertising, mobile and video campaigns, and is expanding to traditional TV advertising marketplaces as well.
But, the first step is creating a commercial that resonates with your target audience.
TV commercials and now Youtube or digital video ads are a great way to reach your target audience before they begin watching a piece of content that they have chosen to watch. You can run your ads before a video that your target audience has an affinity to, thus ensuring that you reach the audiences you need to reach. For example, a washing machine detergent brand may choose to show an ad before a soap opera which housewives are likely to watch. A life insurance company may choose to air its commercials on news shows and sports shows, since the target audience would be working men.
