The main examples of linear algebraic groups are certain of the Lie groups, where the underlying field is the real or complex field. (For example, every compact Lie group can be regarded as the group of points of a real linear algebraic group, essentially by the Peter-Weyl theorem.) These were the first algebraic groups to be extensively studied. Such groups were known for a long time before their abstract algebraic theory was developed according to the needs of major applications. They were considered by Élie Cartan, Ludwig Maurer, Wilhelm Killing, and Sophus Lie in the 1880s and 1890s in the context of differential equations and Galois theory. However, a purely algebraic theory wasn't sought for, until around 1950. The Picard-Vessiot theory did lead to algebraic groups.

The first basic theorem of the subject is that any *affine* algebraic group is a linear algebraic group: that is, any affine variety V that has an algebraic group law has a *faithful* linear representation, over the same field. For example the *additive group* of an *n*-dimensional vector space has a faithful representation as *n*+1×*n*+1 matrices.

One can define the Lie algebra of an algebraic group purely algebraically (it consists of the dual number points based at the identity element); and this theorem shows that we get a matrix Lie algebra. A linear algebraic group G consists of a finite number of irreducible components, that are in fact also the connected components: the one G^{o} containing the identity will be a normal subgroup of G.

One of the first uses for the theory was to define the Chevalley groups.

The deeper structure theory applies to connected linear algebraic groups G, and begins with the definition of Borel subgroups B. These turn out to be maximal as connected solvable subgroups (i.e., subgroups with composition series having as factors one-dimensional subgroups, all of which are groups of additive or multiplicative type); and also minimal such that G/B is a projective variety.

- Any Lie group with an infinite group of components G/G
^{o}cannot be realized as an algebraic group. - The center of a linear algebraic group is again a linear algebraic group. Thus, any group whose center has infinitely many components is not a linear algebraic group. An interesting example is the universal cover of SL
_{2}(**R**). This is a Lie group that maps infinite-to-one to SL_{2}(**R**), since the fundamental group is here infinite cyclic - and in fact the cover has no faithful matrix representation. - The general solvable Lie group need not have a group law expressible by polynomials.

- Borel, Armand. Linear Algebraic Groups (2nd ed.). New York: Springer-Verlag. ISBN 0-389-97379-2.

- Differential Galois theory