What is Proton ?

Atoms can exist with only a proton in their nucleus, as is the case with hydrogen atoms.

A nucleus without at least one accompanying proton, however, is not an atom.

There are three parts to an atom. Protons have a positive electrical charge and are found together with neutrons (no electrical charge) in the nucleus of each atom. Negatively charged electrons orbit the nucleus.

Atoms are the smallest particles that make up elements. Each element contains a different number of protons. For example, all hydrogen atoms have 1 proton while all carbon atoms have 6 protons. Some matter consists of one type of atom (e.g., gold), while other matter is made of atoms bonded together to form compounds (e.g., sodium chloride).

Atoms are mostly empty space. The nucleus of an atom is extremely dense and contains nearly all of the mass of each atom. Electrons contribute very little mass to the atom (it takes 1836 electrons to equal the size of a proton) and orbit so far away from the nucleus that each atom is 99.9% empty space

There are over 100 different kinds of atoms. About 92 of them occur naturally, while the remainder are made in labs. The first new atom made by man was technetium, which has 43 protons.

the components of an atom are held together by three forces. Protons and neutrons are held together by the strong and weak nuclear forces. Electrical attraction holds electrons and protons.

While electrical repulsion repels protons away from each other, the attracting nuclear force is much stronger than electrical repulsion. The strong force that binds together protons and neutrons is 1038 times more powerful than gravity, but it acts over a very short range, so particles need to be very close to each other to feel its effect.

The word "atom" comes from the Greek word for "uncuttable" or "undivided". The Greek Democritus believed matter consists of particles that could not be cut into smaller particles. For a long time, people believed atoms were the fundamental "uncuttable" unit of matter.

While atoms are the building blocks of elements, that can be divided into still smaller particles. Also, nuclear fission and nuclear decay can break atoms into smaller atoms.

Atoms are very small. The average atom is about one-tenth of a billionth of a meter across. The largest atom (cesium) is approximately nine times bigger than the smallest atom (helium).

Although atoms are the smallest unit of an element, they consist of even tinier particles called quarks and leptons. An electron is a lepton. Protons and neutrons consist of three quarks each.

The most abundant type of atom in the universe is the hydrogen atom. Nearly 74% of the atoms in the Milky Way galaxy are hydrogen atoms.

You have around 7 billion billion billion atoms in your body, yet you replace about 98% of them every year!

(This is more advanced information that may not be required at school-level chemistry.)
Protons consist of three fundamental particles, two up quarks and one down quark.

Is there any matter that doesn't include protons ?
Yes, but only in special circumstances that aren't usually included in school chemistry.
Examples include neutron stars and powerful particle accelerators.

is a question that can be answered at various levels of detail and complexity, depending on the context.
This page describes protons at the the level required for high school chemistry (GCSE to A-Level in the UK).