DevOps is a cultural practice in an organisation by development team & operations team to use each other's tool, to smooth out the process of software delivery.
Let's decode the above statement & understand the history behind this. In the early days, with large organisations there was a huge gap in the development team who writes the code, works on design for given requirements & operations team who participate in the change management, escalation point for the users on current product capabilities and enhancement requests. This gap would cause slow business deliveries, let's understand with one scenario, suppose we have a requirement from the business and the development team has build the code according to requirement and it's ready to be released, at this point suppose operations team's release cycle is not in place / will come in few weeks / days, this can cause in delay in shipping the product to the users which eventually get compounded when there can have enhancements from the users in agile environment.
So developers & operations need to come together with their tools to reduce this software delivery time and this can result in 50% faster deployment rate, reduce failures & better recovery time. This can be achieved when team thinks it's a one complete process with shared responsibility, & it's more of a cultural practice.
In order to implement it we follow the priority of People over Process over Tool, also shown in below diagram, which simply states first priority are the people, they should decide based on their knowledge & skills what process & tools to be used & not the other way around, for example someone from the team finds one fancy tool to do one job better which not everyone is familiar about, we should not / avoid that tool because even though that tool does certain job well but the support around that tool gets compromised or there gets learning curve in place for tool's usage.
Feel free to share your thoughts & questions in comments and follow me to understand technical concepts in simple words.