What is continuum in line spectra?

I read that continuum in line spectra is noticed beyond a certain limit. What does it mean?




![enter image description here](https://i.stack.imgur.com/alM6T.png)



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> The four lines in the visible spectrum (designated by α through δ) were the first observed by Balmer. Notice how the lines crowd together as they approach the ionization limit in the near-ultraviolet part of the spectrum. Once the electron has left the atom, it is in an unbound state and its energy is no longer quantized.
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> When such electrons return to the atom, they possess random amounts of kinetic energies over and above the binding energy. This reveals itself as the radiation at the short-wavelength end of the spectrum known as the **continuum radiation**.
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Source: [Chem1](http://www.chem1.com/acad/webtext/atoms/atpt-3.html)


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The energy gap between consecutive orbits(energy levels) decreases as 'n' (energy level) increases. So, the wavelength difference decreases resulting continuum in spectrum.[![enter image description here](https://i.stack.imgur.com/9wDJk.gif)](https://i.stack.imgur.com/9wDJk.gif)


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