Step 1: Given:
\[
\frac{dy}{dx}=1+y^2
\]
Step 2: Separate variables:
\[
\frac{dy}{1+y^2}=dx
\]
Step 3: Integrate both sides:
\[
\int\frac{dy}{1+y^2}=\int dx
\]
\[
\tan^{-1}y=x+c
\]
Step 4: Taking tangent both sides:
\[
y=\tan(x+c)
\]
\[
\boxed{y=\tan(x+c)}
\]