He said: "We had this monolithic code base, around three million lines of code. So when you wanted to make a change you had to test the whole thing and then release the whole thing.
"We split that up into separate applications, so now we have a search application, a coupon application, a booking application etc."
He added: "They are more self-contained, so now you can make changes and do smaller tests. The impact is now minor and you can release components independently, which makes it go a lot faster."
The main challenge that Hotels.com still faces working with agile is that it has an offshore team working on some projects. Silberg said that "agile is hard, but agile distributed is incredibly hard".
However, this is managed by not splitting teams across geographies. So, if a team is working on a shopping application and one on a booking application, one will be in-house and one will be offshore. He said: "We would never have one split across two geographies, the team has to be self-contained."
Agile has become the poster child for effective and efficient development in the IT industry, but many departments struggle to implement it effectively. Government especially has tried to implement it where possible, but has come under fire in the past for not doing it enough.
Silberg said that to get agile right an IT department needs to make the whole company agile first and to also provide effective training.
"This has got to be a top-down approach. Don't give teams an annual roadmap, talk quarterly and allow changes as you go. Don't let finance have an annual budget, make them do it quarterly. You have to get the company to become agile," he said.
"If dev just starts going agile, and nobody else can cope with it, it's not going to go very well.
He added: "Everybody also has to be in the same training course at the same time so everyone is on the same page. There needs to be no confusion and everyone needs to understand their role. That was a real inflection point for us."