Abstract
The Sombor index of a graph \(G\) is defined as
\[
SO(G) = \sum_{uv\in E(G)} \sqrt{d_G^2(u) + d_G^2(v)}
\]
where \(d_G(u)\) denote the degree of the vertex \(u\) in \(G\).
In this article, we determine the extremal values of the Sombor
index of trees with some given parameters, including matching
number, pendant vertices, diameter, segment number, branching number,
etc. The corresponding extremal trees are characterized completely.
